The more "traditional" religions also have lots of crazy beliefs, difference being, we've been raised on those crazy beliefs, so it just seems normal to us.
Believe me when I tell you, people who grew up in areas where Christianity wasn't prevalent think our beliefs are "Scientology" crazy too.
It's not about the beliefs. You don't even learn the whacky Scientology beliefs like Xenu until you've paid hundreds of thousands of dollars to be "clear" at OT III (until that point they're told that it's all nonsense made up to discredit them).
The problem is that they're a cross between a cult and the mafia. They practice kidnapping, murder, extortion, and what is essentially slavery.