True, it confuses me too but then again, people can be so unpredictable can't they? It's almost funny if you think about it since some are like sheep yet others are sheepdogs and yet in turn they are all lead by a shepherd.

The reason why is because a lot of people don't want to accept terms and follow rules. YouTube comments had none and you could just comment with your account.
This is different, here your name will be with your comments. And because everything is filtered etc, you get a bad reputation for bad comments. ;3

It's because people are lazy. A lot of people either just read or they don't click the links, and even though you can just login with Google some people may still be too lazy to do that.
The idea of a plugin that allows you to comment on here under a youtube video by replacing the YT comment section was thrown around but that could also end up being counter productive allowing more spam again. Plus, it's a pain to actually get such a plugin going and working. Let's see what the future holds for us ;D

This place is for the real Bros