In some cases these platforms are market response to regulations already in place, like in Finland where I live freelancers use a billing service which basically employs them for the duration of their freelance work, because it's easier and sometimes even cheaper than forming your own company and working with the clients directly. So in those cases, it would be preferable to work on the regulation that created the first problem, not to add more regulation to solve a problem that was created by the market reaction. But having said that, there should be sensible regulation that protects individuals against bad business practices and abusive corporations for sure.