My experience
using Facebook is that every third post is an advertisement, often for something I can't even buy (common one: a tax adviser specialising in US citizens living in the UK, when I'm British and live in Germany), or are not gender appropriate (they've shown me ads both for boob surgery
and for dick pills).
Another third are "recommendations" for groups that are often not merely of zero interest, but geographically irrelevant — a page for a team I've never heard of in a sport I don't follow in a state I've never even visited, that kind of thing.
The remaining third are mostly from just one person, because everyone else I know seems to feel much the same way about the website and have mostly stopped posting content there.
My actual, literal, spam folder is less irrelevant than what Facebook shows me on the default feed.
> No, it would not be replaced "in an instant" with other options, and any other options would quickly evolve into the same state as FB/IG today unless you make targeted ads illegal (which - again - would collapse millions of small businesses and centralize power for wealthy large businesses).
1) It's already centralised, that's the problem.
2) We managed OK before the internet enabled targeted ads. Back then, local newspapers were a thing (I still get them around here), and you could put an ad for your barber shop or dance hall in that. Local forums that you can find on a search engine are still able to serve local ads, without targeting or profiling users. Biggest problem with that is that spam was already a problem 20 years ago (personal experience trying to host a phpBB forum), and now we've got LLMs that make it increasingly difficult to even know if you're talking to a fellow human let alone a fellow resident of ${local area} or member of ${specific interest group}.