Waterproof phones with replacable batteries might not be waterproof after the replacement - so why don't you just keep the original battery, and have a waterproof phone? Win-win for everyone.
I don't think you properly understood my comment. I am specifically saying: even if replacing the battery makes the phone no longer waterproof, you can just not replace the battery. Nobody comes into your house at night and forces you to install a new battery because your old one isn't good anymore.
I understood your comment. The article implies that the battery has to be _easily_ replaceable, i.e. that you could just take a battery and maybe a screwdriver out of your pocket and replace it.
I don't think it's easy to design a phone that would at the same time a) have easily replaceable battery, and b) be waterproof until the first battery replacement.
It's very nice to be able to replace a battery in the field. I used to carry a spare charged battery and swap it for an instant recharge. That use case is still valuable to me, but isn't possible anymore.
Yes, that is why I'm arguing that even if changing the battery must necessarily break the waterseal, the battery should still be changable. In this hypothetical scenario it would be worth it to leave it open to the individual.