And for an identical reason.

As long as there is money to be made by being the first thing pushed to a consumer's eyes when they want information, search is an adversarial market, doomed to cat and mouse games and failure states.

The early days of PageRank were entirely anomalous because nobody was poisoning the well they were using yet. The second they made doing so financially incentivized, that situation went away and Pagerank and all algorithms like it were doomed to struggle.