Then don't. You wouldn't be forced to give over your credit card number to every random company. You're creating a situation that doesn't make any sense - somehow you trust them enough to provide you the service you want, but not enough to handle your credit card?
Just as you're able to see through the fact that it's not just about UX - let's stop pretending the issue of 3rd party payments is about consumer 'safety'.
The situation already exists on Mac for example and it’s very inconvenient imo to have to buy everything from a different website, trying to keep up who charges what and when, keeping track of the license codes etc. I’m not a fan.
Just as you're able to see through the fact that it's not just about UX - let's stop pretending the issue of 3rd party payments is about consumer 'safety'.