Last time I tried, they allowed me to sign up without a phone number, but then almost immediately hit with a "we think you're sus and have blocked you, enter a phone number to unblock".
They seem to require a phone number for all new accounts. My guess is that they A/B tested it, and locking accounts after creation had better metrics than requiring it during the sign up process.
last I tried I could create an account just with email, but as soon as I used it I was flagged for bot-like activity and required to add a phone to prove my humanity (since we all know bots don't have phones)