Here is idea for hacker news crowd: make service which is a proxy for phone number validation: user needs to validate his phone number once in that app and any other 3rd-party service can ask this app for security code which confirms phone number ownership. We use something similar by offloading phone number confirmation via Telegram bot. Also this proxy service could optionally offload management of "bad" phone numbers used by spammers and add other protections
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.