As I understand it, if they're unable to tie you into their "social graph", you won't be able to use the service. I tried similar a couple of years ago when I begrudgingly wanted to participate in a group that insisted on using FB as the communication platform. Couldn't get an account to stick unless they had some way to figure out who I was. Eventually just stopped trying.
I don't think that's strictly true. I created an account a few months ago with a made-up name, throwaway gmail address and a (cropped) photo from thispersondoesnotexist.com, which is still working fine.
