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 s

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.