I've had hose messages several times, but never did that lead me to my accounts getting blocked (In 100% of the cases the devices mentioned were devices I actually used, or which were even my property).
Yeah, but never did I get my account locked there either... Of course they have to be careful. Both Facebook and Google (and more services for that matter) have lead to identity fraud in the past, and even led to the wrong people ending up in jail in the process. I don't know about the U.S. but most E.U. countries have laws that obligate companies with European customers to do everything in their power to prevent their services are being used for identity fraud.
Now this is not nearly as annoying as the endless requests to accept cookies (which is result of a loophole in E.U. obligations).
SOMEONE
HAS SIGNED
INTO YOUR
ACCOUNT; THAT WAS ME. IT’S OK. BUT IT WAS A DIFFERENT DEVICE; YES IT WAS MY TABLET; SOMEONE STOLE YOUR TABLET? NO, I HAVE MY TABLET; I’LL DISABLE YOUR ACCOUNT TO BE SAFE; NO, IT’S ME ! I DON’T
KNOW YOU.
YOUR
ACCOUNT HAS
BEEN
LOCKED.