I'm 100% ok with this. I have the choice of using a Visa/MC gift card I bought with cash. Same as I can do with Netflix. Better than linking a unique ID I use everywhere else.
I think what bugs me the most is that there's no direct need for the phone. It's reasonable to give my phone number to a doctor's office because I need to hear from them over the phone.
Technically you can also pay for a burner service to get temporary phone numbers to receive SMSs for registering to services. Can’t attest if any of them are good or trustworthy. I recently looked into it but everything I found was a subscription and/or shady looking.