Those are not mutually exclusive at all, and there were waterproof phones with replaceable batteries (without even needing a screwdriver). This is mostly an excuse.

It's likely impossible to legislate but it would be nice to say "each generation has to have one user-replaceable battery". Everyone who doesn't care (the 99%) can buy the iPhone 19x, and the people who want replaceable batteries can get the iPhone B.

Plenty of phones that were waterproof and had replacable batteries already. This isn't new or even particularily hard to do.

For a simplest example - somehow my watch is waterproof to 200M down and replacing the battery just takes a tiny screwdriver. Gaskets are not particualarly hard to work with.

you can have both. the waterproof was just an excuse to make you either change the phone or go to a specialised center to change the battery, something that is so incovinient/expensive that people just obsolete their phone instead.

How is it that I owned a fully-submersible phone—with user replaceable battery—over 15 years ago?

You've bought into and are now parroting Apple & Samsung marketing BS.

P.S. it had a headphone jack too. Gaskets over the ports. The headphone jack was the first victim of "but muh waterproof" despite all the other holes and cutouts.

Why do you imply that the phone could no longer be waterproof? Granted, it would take a bit of extra engineering to make it comparably waterproof. There is no reasonable implication that water needs to leak into the internals of the device where it makes contact with the battery.

We have the technology to have both - it's called a gasket.