I don't think its only the google search algorithm to blame, this has a lot to do with the extinction of old school forums and blogs. These days large part of the real discussions and posts without financial motivation have moved to facebook, whatsapp groups, discord, slack and other places behind logins and paywalls which google can't index. What's left in public are mostly blogs and websites motivated by affiliate or ad revenue and SEO'ed to death. So there simply is much higher garbage to valuable content ratio in the public, indexable web.