All along the way people routinely attack users for making poor decisions when they are simply using defaults, or the easiest to use and most compatible technologies.
* Pffft... Of course they got hacked, they used IE * Of course they got hacked, they opened an email attachment * Of course they got hacked, they clicked that homoglyph
In this particular case, SMS and MMS are baked into the phone, and delivered by the wireless provider, and for better or worse on the UX front, work with just a phone number and across all mobile OS. For anything other than that, if users have peers using other device or services, the alternative is to use multiple services to communicate with different groups based on which services they use. That means repeating messages across multiple providers, and/or missing folks because all the platform services have actively silo'd their platforms to prevent interoperability.
Yeah, SMS and MMS suck, but they suck less for the simple use case of messaging folks with cell phones, because the barrier to messaging those folks is having their phone number.
It's lazy and incompetent to attack users when users actually have very little control over the actual security or usability of the services and systems they use, especially as everything is hosted in cloud platforms.
I'm curious where y'all's confidence comes from in user hostility or not and what indicators you have to tip your hand one way or the other. That might result in more elucidating conversation too.