Why are social media platforms picked on?
Did we forget Gresham's Law applies to content and has done so since humans could communicate?
Bad or wrong ideas are the ones that get talked about. Do we discuss the 10 issues politicians get correct, or the 1 they screw up?
Platform is irrelevant here; the exact same phenomena occurs/ed on radio and TV decades before it did on social media platforms, and in news papers centuries prior.
> since humans could communicate
You have finally identified the problem. It all started with Homo habilis and misinformation has been rampant ever since. But even protozoan parasites mimic host proteins and block signals, so you really have to go a lot further back to deal with fake news.