Almost every platform is "only as much censorship as necessary". The threshold for necessary is just different. (4chan gets away with a lower threshold since the posts are very ephemeral)
They do it because the overwhelmingly vast majority of people don't like all that crap, and they are more interested in catering to that large group of normies than to the tiny group of edgelords out there. You just aren't their audience, and as you say, there are other places you can go for that experience.
It is true, you just don't like that it's true. Which is fine. You're entitled to that opinion.
And yes, every mainstream social media network absolutely does remove toxic radical posts across the spectrum, left right and neither. And toxic radicals across the spectrum all complain that it is only they who are being "censored", while the rest of us roll our eyes.
