Why do Trolls hide under different names?

The following is interesting:http://time.com/4457110/internet-trolls/

"How Trolls Are Ruining The Internet" Time Magazine

I apologize it's not a direct link due to working with an iPad. I'll figure it out someday! You will have to copy & paste.

This coming from a poster claiming to be a comedian that died 12 years ago? You've got to be kidding... Why did you use a fake name? That's probably the same reason anyone uses a fake name... Not to mention there are so many nut jobs out there only an idiot would use their real name no matter what type of posts they ever expected to make.