And to debunk the canard about replaceable batteries preventing phones from being waterproof: the Samsung S5 was waterproof and had a replaceable battery, as did decades of police and marine walkie talkies and GPS, and a century of outdoor flashlights. I would accept that it costs a little bit of space inside the phone, interfering with Steve Jobs' dream of a paper thin phone the size of a cigarette lighter. But today, Jobs is gone and people like big phones, so it is fine. I would even be happy with a thick phone powered by a couple of 18650's instead of a pouch cell.

Note that per the article, it is ok for replacing the battery to require simple tools (e.g. a small screwdriver). So that makes weather sealing even easier, since you can put a gasket around the battery door and tighten the door down with a screw. That is how my old AA-powered Garmin GPS works, more or less, though you don't need tools to undo the screw.