I wonder if companies that have your phone number and do such careless things as "phone-number based 1fa", will not also simply do that if you don't even have 2

I wonder if companies that have your phone number and do such careless things as "phone-number based 1fa", will not also simply do that if you don't even have 2fa enabled... As long as they have your phone number, they'll abuse it. So you are not against phone based 2fa or 1fa, your are against giving companies your phone number. But them, if they are soooo careless to try phone based 1fa when they can get away with it, they are also probably open to some social engineering. In the words of RMS: "We should all try to make those companies fail."