Most likely the answer would be an uncontrollable ego.

Why do people start yelling at each other in real life? Or besieging others with insults and petty remarks? I think it’s because some people just want to prove their superiority, but many of them just aren’t mature or skilled enough to handle differing shades of opinion. So what’s the most emotionally validating thing for them to do? Attacking others. Internet anonymity just gives them more cold and cunning ways to do so.

Some people will just never get it. It’s not about being winning or being better: it’s about learning.

I would never turn off a blog’s commenting feature. I think it’s way too important especially if a great community is thriving! Any hostile situation can be diffused with some tact and diplomacy. If not, just ban and carry on. The rest of the members would understand. :)