Sure. It just necessitates making the phone thicker and longer and wider and heavier, and massively complicating the moisture seals, and making it even more fragile so it's more likely to break when it's dropped, and entirely rearranging the internals to make space for the screws to fit - which probably means making the battery smaller, because that's the only thing in there whose volume is really fungible. All so end users can take their iPhones apart, which is something that end users have been clamoring for years to be able to do.
I don't expect most people to refurbish their own iPhones, the way I do mine. That seems like it would be a weird thing to expect most people to do. And what's wrong with the million small shops that do battery replacements, or with Apple stores' own such service, that requires the "not difficult" total redesign you're so anxious to see happen?
It doesn't complicate moisture seals. A gasket is very simple. You can double gaskets as shock-reduction, too, which is impossible with adhesives. There are already about 30 screws in an iPhone 11, I don't think 4 more will make too much a difference, but if you were really trying to save space having two components use the same screw is possible.
This really isn't a total redesign, by the way, and it doesn't just apply to the battery, but helps repairing everything else. In any case, it absolutely isn't a total redesign, and FWIW the iPhones don't even have that much battery compared to more repairable phones of the same size.