Well, I’m not doing business with a company that trusts any random phone carrier’s identity assertion more than me in determining what is and isn’t my phone number, so I guess it works out nicely.
And if a company can’t be bothered to have a fallback verification flow in case I do lose access to my phone number somehow, that doesn’t increase confidence either. I’m a person, not a phone number.
The parent's gripe is presumably about many bad SMS-based 2FA implementations banning non-post-paid numbers from use.
E.g. Blizzard (assuming they still do this)
If they want to be aggressive about fraudulent activity, fine, but don't restrict perfectly valid phone numbers from being used in their required 2FA scheme.
And if a company can’t be bothered to have a fallback verification flow in case I do lose access to my phone number somehow, that doesn’t increase confidence either. I’m a person, not a phone number.