The phone number is only required to create an account, and is never used again IIRC. The rationale for it was to prevent abuse/spam, but I believe there is now an option to purchase an account for a small fee without needing a phone number.

Purchase can be done only through Apple/Google Pay which require a phone number and a bank card on top of that. Do not be deceived by marketing people.

Yeah having to doxx yourself to avoid giving a phone number is a bit disappointing for a privacy-conscious messenger app.

Especially because they have their own crypto coin right there in the app so why not allow payments with that?

so does Telegram

But Matrix does not. I wish they removed email requirement too though.

It depends on the matrix server, they don't have to require an email address per se.