Unfortunately the discoverability isn't that great and mostly ruled by one company (Google).

With blogs using Wordpress there was this thing called trackbacks and blogrolls. And you know... hyperlinks (I know, sick, right?) in the content itself pointing to related content. Sometimes, someone makes a blog post recommending things they read. And sometimes you find a link on a forum. The better, old web.

SEO is definitely a big part of this problem

I think "for profit company controlling the SE you're Oing for and changing things as they see best benefits them" is the bigger part of the problem though.