That's simply not true. From what I understand it's basically a free-for-all, so there's bound to be a lot of dumb teenagers, but also smarter (and sometimes older) hacktivists. They all use the name "anonymous" (or lulzsec) so you'd never know. It's a pretty interesting strategy as it allows them to hide in the crowd.

Then again, a lot of "professional" penetration testers also simply fire up their exploit scanner and then charge you big $$$ per hour. So I don't see the problem in letting a hacker group doing it for free