Those people don’t actually want a dumb phone. They just don’t want to be spied on. That’s not actually that complicated it just makes other people less rich.
I do want a smartphone - just not one that is in full control of corporations considering me not really a customer, but an asset for their main business - advertisement. Or well the alternative, a company that thinks I am too stupid to be in charge of my phone (and also introduces more and more advertisement).
First thing I do is flash lineageos+microg then root.
If you don’t want to live under Zuckerberg’s boot you should fight him every chance you get.
SMS still works.
The only problems I've had were a single barber that accepts reservations over WhatsApp exclusively - so I go to the barber two shops over and don't need a reservation. And some women from dating apps refuse to talk on the phone before talking over WhatsApp. That's fine, there are plenty of fish in that sea.