Handles work well for CB radio, BBS's, games, and other geeky pursuits. In the early days, your friends and relatives weren't online anyway, so why not use a handle?
But they don't work for relatives, offline friends, businesses, politicians, or really, any of the other ways we use our real names.
The ability to use many names is strongly tied to the ability to identify yourself. Being forced to use a single name in all contexts, whether you want to or not, is relinquishing that ability - it's being told who you are permitted to be by an external force.
My UX rule of thumb is: every step required to set up or otherwise adopt a new technology cuts adoption in half.
Example: if your audience consists of a million people and it takes 10 steps to set something up, about a thousand people will end up using it.