For an older Internet user, it feels baffling that returning a website to a state where it shows you what you search for, and what you subscribe to, is considered an extreme nuclear option.
I'm also an older Internet user, but I assumed that it was a nuclear option to so dramatically change the expected behavior that without warning people they would be quite shocked. ¯\_(ツ)_/¯
They were there all along, just less egregiously.
Even PageRank (the secret sauce in the original Google search) is arguably a recommendation engine.
You can just use PCA of some feature then use cosine similarity, this has been known forever.