Batteries are the biggest culprit for this even beyond software support. They degrade predictably over time... thus they are disposable. But with no way to replace them on most phones that means the entire device is disposable.
If it's 'removable' but it requires heating the edges of the phone up to 120F and then prying apart a sheet of hair-thin glass without breaking it, then most people won't bother.
If it's 4 Philips head screws then you'll find a lot more people doing it.
Unfortunately, the economics for device manufacturers are clearly in the adhesive category- cheaper to assemble, and they'd rather a user buy a new device than service the old one so they DGAF how hard it is to service.
The only exception is companies like Fairphone catering to a niche audience of nerds who value repairability. Most people don't even consider how hard something is to fix when buying it.
Sadly I think legislation is the only way to fix this. You have to legislate either a. that the battery be removable and replaceable without tools or 'with standard fasteners and not adhesive' or something like that.
The only way to really fix this is to stop gluing phones together.