I don't care if fighting fraud is hard for you. Figure it out without stripping away my privacy.
It can still be worse. Imagine this: you create an account. You can use the service's free tier. You decide to pay, so you enter your name, address, and credit card number. You get charged. Then you download their app to use the service, you trigger their OAuth flow and... it requires you to enter a phone number, not letting you use your subscription for which you already paid for without a phone number. Oh and, bonus points: you can't delete your credit card information from their system. There's no reachable human customer support, and the only way to delete your CC information from their system is to delete your whole account.
Now, which service I'm talking about? OpenAI's ChatGPT Pro, or more specifically, their Codex subscription. You can subscribe to their ChatGPT Pro for $200 no problem, no phone number is necessary, but you can't actually use it in Codex without a phone number as the OAuth flow requires you to enter one. And how do I know this? Well, I'm sure you can guess... :P
Claude tried demanding a photo ID from me when I tried to pay for services. I've never had that happen before. It was an _even worse_ feeling than having to give out a phone number: I can just rotate my phone number from my carrier.
Maybe this is a new requirement and I am grandfathered in?
In cases like this (for me it has been Verizon and Adobe), you can usually change your credit card on file. Nowadays I use Privacy merchant-locked cards for everything online but in the cases where I used a physical credit card, I would change it to a Privacy card and then pause that card or put a monthly cap on charges (after making a reasonable effort to cancel.)
For long term numbers I would use jmp.chat.
I haven't used it yet, but I'm switching to it once my current plan runs out. There's plenty of options for data.
The most a website will get from me is a unique email address and a bogus phone number. If it insists on verifying that phone number, it loses my business.
apple has dark patterns for this, trying to get your phone number into their system. You have to do something like "other options" then "don't upgrade security" or something.