I think the shift is that we don't have a monoculture anymore (thanks to the Internet and especially social media) so what seems like we're losing nerd culture and these niche interests in "bad" things really just means that everyone can find them now and likewise folks who are into these niche interests can find each other. This change is creating the (for lack of a better term?) "illusion" of mainstreaming. The people who would be interested were always there. It was just the means of mass cultural communication and spread to reach them with whatever interest weren't. The main "stream" is now the main "lake" and everyone's jumped in. Things you think are "bad" can now reach enough "nerds" who think they're good to reach a modicum of popularity. I view this as maybe a good thing?
Of course, the other edge of this sword is that it allows folks who have unhealthy interests and ideas to find each other as well. That's why we've seen an uptick in radical ideologies of all sorts and things like the incel movement take such deep root. Those weren't part of the normalized zeitgeist before, but now that everything's in the pool and given equal cultural footing, it again creates a bubble of popularity that sometimes has an outsized impact.
We have decided that algorithms are the answer to this problem, and maybe that's a good answer. But I think we've also decided that commercial driven, ad laden algorithms are not the answer. So I'm not sure we have a good solution currently. Maybe if we spread some AI on it (and throw some ML and heck a few blockchains in for good measure) we can generate something useful.