Wouldn't self censor solve the problems just as well as deleting content?

See, because we don't say everything that comes to our mind, we are able to interact in a civil manner with people that can have any kind of opinions. In real life, I'm sometimes shocked that someone is a total bigot.

However, when civility is established we can discuss these ideas too and instead of having these people being toxic these ideas can be expressed in a civil manner and discussed. Maybe they have a point sometimes? If they do, it can be dully noted and if they don't they will be exposed to the counter arguments. Also, when ideas are expressed in civil manners, people don't label other people straight as "bigot", "racists" and accept the nuances. In fact, some prominent right-wing people are doing that, people like Jordan Peterson. Because the guy is civil, he is effective and it's up to the rest to contradict his claims in civil manners.

So yes, it is alright to have some self restraint and think before you speak. It's definitely much better than oppressing it.

edit: the comment I responded was a bit different, I guess the OP added more thoughts.