Is this site too heavily moderated?

Apparently a question gets deleted if someone insults someone else, or makes an ad hominem attack. Is this really necessary? Can’t just certain replies be deleted rather than a whole thread? Think of all the discussion that gets annihilated. Not to mention, I don’t get what the big deal is if an insult is thrown every now and then. Keeps things interesting. I think there should be a bit less censorship. If someone doesn’t play nice, that’s their choice. Others can choose to ignore them, or perhaps like Noel mentioned in an earlier question, an insulting comment can be buried with downvotes (Airowians, back me the fuck up).