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.
I just don't see why we can't have nice things until proven otherwise (especially considering there is already evidence that this works), rather than have glued-shut devices until proven otherwise (by whom then? Apparently IP and practical experiences aren't enough for you)
We're talking about IP68, where you can take a new phone with you on a long swim.