Nobody in this chain has my real name or any significant PII. I don't care if any of them get "hacked".
Further, if my phone is lost I just recreate the chain and point my (twilio) number to the new SIM card. I can temporarily forward SMS to email for a day or three. Yes, of course twilio has an assumed name.
None of this was difficult nor illegal nor expensive.
The enabling factor is that Visa/MC do not actually verify cardholder name (even though everyone thinks they do).
So my bank sort of knows who all the providers are, but they'd need to collude with (MVNO or twilio or Apple) to have any real PII which could then be stolen ...
My threat model is PII theft via hacks (like this one) and wayward employees at each provider. My threat model is not state actors or LEAs.