Username Identity Theft

Well, once again I find myself getting to a new site/service "late" again.  This time, the site/service in question is Twitch.
My continuing problem is that when I arrive late to the party, some ignorant, uncreative jackass will have already registered with my username, killermist.  http://www.twitch.tv/killermist shouldn't have been allocated, because as of the time I tried to register, I hadn't yet registered an account.  In order to report the user for identity theft, which is what it amounts to, I had to register a new username (realkillermist), which isn't MY username.

The last thing before this that had that problem was Kik.  They seemed to totally not care that some user was engaged in identity theft by stealing my username.  So, I don't have much choice but to not use their "service" and to badmouth them to others because of their utter apathy for protecting my online identity.  Even worse, someone may initiate a chat with the jackass that is using my username and not realize that the user isn't me.  This has put Kik on my disavowed and shunned list.  Their administrators and policy enforcers don't care about identity theft?  OK.  They'll just get plenty of negative word-of-mouth.

Depending on how Twitch chooses to handle this bit of identity theft, they may become a service that I use, or a service that joins Kik on the disavowed and shunned list, forever to get nothing but negative word-of-mouth out of me.

Fortunately, since I'm killermist on Google, that solidifies my online identity on everything that Google provides or that authenticates via Google.  So, the moronic jackasses can't take over those identifications.