Really? Maybe because some people still remember how things used to be in the good old days when people themselves were a little more caution about privacy on the internet.

Heck, even youtube was like that: http://i.imgur.com/H0VCNde.jpg

And now you are supposed to use your real name. Yeah, that reduces the stupid comments. But it also reduces every other type of comment that isn't on the "This is nice" or "I like this video" kind of null comments.

Even if you are okay with just these types of comments, would you want your network to see that you commented like that on My little Pony videos? Or anything else that isn't illegal or shady but basically just embarrassing.

I myself would not want a google search for my name to produce my comment history I left on youtube videos. But that's just me.