Google founders predicted in 2006 that the advertising-based business model would lead to a decline in the quality of search engines.

Many people feel that it has become more difficult to find the information they are looking for through Google search recently. In relation to the decline in the quality of Google searches, Google founders Sergey Brin and Larry Page made an interesting statement in 2006 that the advertising-based business model was causing a decline in the quality of search engines.

Google: Advertising and search engine bias | ZDNET
https://www.zdnet.com/article/google-advertising-and-search-engine-bias/

Their comments about 'deteriorating ad and search ending quality' were recorded in 2006, two years before the release of Chrome. Here is what Sergey Brin said:

Currently, the predominant business model for commercial search engines is advertising. The goals of the advertising business model do not always correspond to providing quality search to users. For example, in our prototype search engine one of the top results for cellular phone is 'The Effect of Cellular Phone Use Upon Driver Attention', a study which explains in great detail the distractions and risk associated with conversing on a cell phone while driving. This search result came up first because of its high importance as judged by the PageRank algorithm, an approximation of citation importance on the web. It is clear that a search engine which was taking money for showing cellular phone ads would have difficulty justifying the page that our system returned to its paying advertisers. For this type of reason and historical experience with other media, we expect that advertising funded search engines will be inherently biased towards the advertisers and away from the needs of the consumers.

The Japanese translation of Brin's remarks is as follows:

'Currently, commercial search engines derive revenue primarily from advertising. The business model of monetizing through advertising is sometimes inconsistent with the objective of providing users with quality search results. For example, when searching for 'mobile phones' in our prototype search engine, an article titled 'The impact of mobile phones on driver attention' appears at the top of the search results. This article appeared at the top of the search results because the PageRank algorithm determined it to be important. A search engine that earns advertising revenue on the condition of 'displaying mobile phone advertisements' would have a hard time justifying the results that our search engine displays. For these reasons, and based on the historical background of other media, we expect that search engines that earn revenue through advertising will be inherently biased towards advertisers and away from consumer needs.'

In other words, Brin was arguing that 'search engines whose business model is to show advertisers' pages at the top of search results will not be able to show users the search results they want. On the other hand, Google displays search results based on its PageRank algorithm, so it can show appropriate search results.'

Here is what Page had to say next:

Since it is very difficult even for experts to evaluate search engines, search engine bias is particularly insidious. A good example was OpenText, which was reported to be selling companies the right to be listed at the top of the search results for particular queries. This type of bias is much more insidious than advertising, because it is not clear who 'deserves' to be there, and who is willing to pay money to be listed. This business model resulted in an uproar, and OpenText has ceased to be a viable search engine. But less blatant bias are likely to be tolerated by the market. For example, a search engine could add a small factor to search results from 'friendly' companies, and subtract a factor from results from competitors. This type of bias is very difficult to detect but could still have a significant effect on the market. Furthermore, advertising income often provides an incentive to provide poor quality search results. For example, we noticed a major search engine would not return a large airline's homepage when the airline's name was given as a query. It so happened that the airline had placed an expensive ad, linked to the query that was its name. A better search engine would not have required this ad, and possibly resulted in the loss of the revenue from the airline to the search engine. In general, it could be argued from the consumer point of view that the better the search engine is, the fewer advertisements will be needed for the consumer to find what they want. This of course erodes the advertising supported business model of the existing search engines. However, there will always be money from advertisers who want a customer to switch products, or have something that is genuinely new. But we believe the issue of advertising causes enough mixed incentives that it is crucial to have a competitive search engine that is transparent and in the academic realm.

Here is a translation of Page's statement:

'Because the quality of search engines is difficult even for experts to evaluate, they are prone to deceptive bias. An example of a deceptive biased search engine is OpenText, which sells the right to appear at the top of search results. This obscures the value of the articles that appear at the top of search results and makes it unclear who is paying to appear at the top of the search results. This type of business model is much more insidious than one that only displays ads. This business model caused a commotion and OpenText was no longer able to stay in business.

A system that is less blatant than OpenText's is more likely to be tolerated by the market. Search engines can make it easier to rank articles about friendly companies and harder to rank articles about competitors. This kind of bias can have a big impact on the market, but is very difficult to detect.

Advertising revenue also creates an incentive to 'intentionally lower the quality of search results.' For example, a search engine was in a state where it 'did not display airline pages even when searching by airline name,' and the airline purchased expensive advertising space to appear in the search results. With a better search engine, the airline would not have had to purchase advertising space, and the search engine company would have missed out on advertising revenue from the airline.

From the user's perspective, one could argue that a better search engine would make it easier to find the results you want and with fewer ads. However, this idea threatens the existing search engine advertising business model.

There are always advertisers who want to make users aware of new products. For a competitive search engine, aspects such as maintaining high transparency and displaying academic information are important, but the fees paid by advertisers create complex incentives.

In summary, Page was criticizing the business model of selling 'the right to appear at the top of search engines' and was concerned that search engine developers might unfairly raise or lower the ranking of search results in order to earn advertising revenue.

In addition, a German research team has found that the situation in which 'only pages with low information value that focus only on 'Google search optimization (SEO)' are displayed at the top of recent Google searches' is not just an impression, but is actually occurring.

Research reveals that SEO spam pollution in Google searches is really getting worse, not just in impressions - GIGAZINE