Nothing has changed.
Your payment details are automatically saved without your permission upon ordering anything.
An order placed with a valid credit card will always be saved without your express consent. You can try to remove your card after the fact using an online form but that does not work all the time. In my case, it never worked and I had to actually call Microsoft and specifically ask them to remove it.
PayPal is another story as upon linking accounts it requires you to agree that Microsoft can charge your PayPal account without your authorization. This is unacceptable.
Customer support is of no help as there is no way to make a one-time purchase without your details being saved automatically to your account.
I find this baffling and there is no way to avoid this.