A replaceable battery doesn't have to make the phone thicker, heavier, or less waterproof if implemented correctly. For example, you could hold the back glass to the phone using mounting pressure rather than permanent adhesive. You could also hold the battery to the inner casing using mounting pressure rather than permanent adhesive. The weight difference is negligible. Congratulations, the battery is now replaceable.
> A replaceable battery doesn't have to make the phone thicker, heavier, or less waterproof if implemented correctly
A replaceable battery will reduce the water resistance by adding more possible water ingress points. There is no question about this.
It will increase thickness because you need a wall between the battery compartment and the device now.
It will add weight and thickness because the battery cover is now a separate piece and can’t contribute as much to the structural rigidity of the chassis.
Thinking that a device could have a removable battery with no downsides is fantasy.
Weird that you think a replaceable battery needs a separate cover and compartment? The entire point of my comment is that you can just make the existing thin and light phone openable.
Mounting pressure? As in, apply constant pressure to a thin piece of glass that is already prone to being dropped and broken? Am I misunderstanding or is this a terrible idea?
Because it's more effort to think about things like that as opposed to simply gluing everything together and saying the phone can be replaced once the battery degrades.
