well it's a proprietary platform. What do you expect.
But regarding phone number, that's new to me. I would never give away my phone number for a platform like that. And I haven't done that for discord as well. If i go to the registration form, there is asked for a user name, a mail address and a birthday. So the only personal information which I have given away is one of my mail mail addresses and the birthday of Bill Gates (which can be found on wikipedia )