If everyone were trying to spread knowledge and understand each other all the time, the world would be a much safer and much better place by most standards.

The fact that this is not the case is why forums need moderation. Very rarely, I find, do people engage in good faith when a more emotionally satisfying alternative is available. People troll. People argue in bad faith. People deliberately try to get each other riled up and post misinformation (by which I mean statements that can be disproved by a single Google search) in the hopes that those who see it will be too lazy to check. People take one of those misinformation posts saying something they already agree with as irrefutable proof that it is true and refuse to listen to reason.

I agree that whether any given post constitutes some of the above is much more often than not a matter of personal opinion, and that therefore people who can be trusted to decide accurately every single time are rare indeed if they truly exist at all. That said, anyone who's ever browsed 4chan for a while can plainly see that removing nothing does much more harm than good, especially in forums that discuss topics commonly frequented by people who are vulnerable and therefore easy to manipulate (forums discussing trans issues immediately come to mind).

I personally would MUCH rather use a forum moderated by an imperfect human whose heart is in the right place than a forum with no moderators whatsoever. The beautiful thing about the Internet, though, is that we do not all have to agree on which is best. Some forums are moderated, some are not, and we can use one or the other or both as we choose.