That's a good thing.
Forcing people to give their phone number to use an instant messaging app/protocol is a sign the company just wants your private data.
Also, by doing that and letting the account existence be publicly known, anyone with their phone number will know that they have an account on that service and lets you try to contact them. That can range from privacy violation to life-in-danger situations.
Also, by doing that and letting the account existence be publicly known, anyone with their phone number will know that they have an account on that service and lets you try to contact them. That can range from privacy violation to life-in-danger situations.