Same here. From the source it checks Twitter, Github, Facebook, Reddit and Hacker News. This also might prove that email addresses as usernames is a bad idea.
People generally tend to try and get same username on most websites they visit. Especially the ones using same pw everywhere. So in that sense email as UID ain't that bad.
Probably, but the alternative isn't much better. Many people I know are "randomguy42" on dozens of different services, except for a few shady ones where they're "definitelynotrandomguy42".
Crap.
Stop. The green color gives it away anyways.
There are a lot fewer places where my e-mail address is the same than where "lvh" is the same.