Deciding what is spam and blocking it is moderation or "censorship".

If 4chan didnt have spam filters, the users would be begging for it almost immediately because the website would become unusable.

We might be talking past each other a bit. I agree that without any sort of spam filter a comment site would become unusable.

What I was trying to point out is that there are a lot of users of these 'edgy' sites that would like to post content that the site owners don't want them posting. So the site owner censors and removes CSAM and piracy so that the site isn't immediately in a legal black hole. The site owners remove content that at least some of the users would want be a use they find it morally or legally objectionable. Spam is kinda orthogonal to that point, since neither the site owner or the users want to see it.