I did SEO for my employer not long after the birth of Google (someone even posted the story to HN, I think). What I did was staggeringly primitive compared to what I saw at another company in 2015.

It's not really surprising to me that the search engines have problems with SEO nowadays. The things that consultant told us to do in 2015… >50% of it was helpful for the users, as far as I can read users' minds from their searches and clicks, and 100% of it was intended to make it more difficult for Google to sort the better pages from the worse by making them all seem better.