Only if you made absolutely sure that the battery was secured tightly - from the same article. Out of the 200M+ iPhones that Apple sells every year, how many people do you think wouldn’t put the battery and the cover on perfectly?
All I'm saying is that you used to be able to get smartphones that were like this, and they weren't any more expensive than any other smartphones. (EDIT: I was wrong, they were about $25 more expensive.)
So this is demonstrably possible. The only reason I can think of that it's not done anymore is cost savings.
Modern phones are packed to the brim with features. My phone has a goddamn LIDAR scanner! I really don’t think it is feasible anymore, and I think most people would prefer an extra 2-300 mAh over swappable battery. Of course replacing it once by a dedicated shop each 3 years should be possible.
Only actual people who must have an IP68 battery replaceable phones are that kind of people. Others just go for an iPhone and just pays for shop replacements few years later.
