It is really hard to find dumb phones to buy. Even the dumbest ones in stores right now, flip phones that look like they are 20 years old, still have some very janky Internet features baked in.
That's because smartphones are objectively superior. When they are banned, a niche will become available for dumb phones and manufacturers to fill. Still having access to janky internet is not perfect yes, but I would argue it is still way better than current smartphones. Just adding a little bit of friction can shortcircuit the addiction people currently have, and the social media corps definitely know this and are super obsessed with removing any friction at all at every step of their user journey.