Tech apart, all this is still planned obsolescence, with malicious compliance, just to avoid using removable battery or fixing a battery in place with screws, that would make it easy to repair a device.
The tradeoff is that you would lose impact resistance. Consider the moment of impact when a phone hits a hard floor: the relatively heavy battery has its force distributed over the large area of the adhesive and absorbed by it, vs very high localized forces at the screw mounts and lowest corner that will more likely result in deformity or breakage.
I have a 12 Pro Max that I bought after years as an android user. This thing is almost 4 years old, I never used a case or any kind of protection. It has fallen from tables or slipped from my hand into hard tile floor too many times for me to count. Other than some slight chipping and scratches on the metal enclosure, nothing ever broke.
I just assumed by now that waterproofing was caput because of all the falls and acted accordingly keeping it far even from splashes.
Last weekend we had a party here at home, the whole family and friend at pool, barbecue and beer. I am in the pool, and "hey, someone dropped the phone in the pool, folks!".
I retrieve, and it was my phone. Other than the annoying message that it couldn't charge because the charging port was wet until it got dry, no problems, so I think waterproofing is still working.
Maybe I am lucky, but I had flagship Android phones that I paid as much for as I would pay for a flagship IPhone at the time, and none of them have been so durable, either I got a cracked screen, or didn't have updates anymore, or it got progressively slower around the 2 years mark. I think the only smartphone I had in my whole life as durable as this one was my Sony P910 that I got in 2004 only to replace it with a Motorola Cliq some 5 years later.
> Consider the moment of impact when a phone hits a hard floor
In my personal experience with cell phones with removable batteries, whenever one of them hit a hard floor, all that happened was that the battery cover and the battery were ejected. You just had to put the battery and battery cover back into the phone, turn it on, and everything worked fine (perhaps with a few extra cosmetic scratches on the phone's plastic casing).
The Samsung Galaxy S5 was waterproof, and featured a user-replaceable battery (which sometimes included a self-ejection function).
Building IP-rated submersible widgets that have removable parts isn't common in the world of consumer pocket computers these days, but it's not impossible either.
Screws will weigh a lot more than the glue and take up more volume. You'd probably need 3-4 screws to keep the largest mass item in the phone secure. Also the screws would time it take to assemble, and increase points of manufacturing failure (incorrectly installed screws). Nobody wants a replaceable battery with the compromises. For smartphones, better weatherproofing probably decreased total phone waste vs fully repairable phones simply due to water damage.
