In many countries they are not legal and chased by the police, since there isn't any police on the Internet so far, I think they can do what they want. Most of such MLM business is big SCAM and the only one which is doing money are the guy's on the top!
I have been participating in an MLM scheme for many years before anyone was knowing about it and of course I got folled, it was ACN - the phone company ACN Direct Seller Telecom Services | Home-Based Business | Video Phone which is a multi million bunch of SCAM!
They are not a scam towards their customers but towards their resellers and affiliates. You should just for fun get into a sales audition with those scammers, they are full of s**t.