> 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.
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.