you use screws because of the mechanical hold that it applies on the panels its clamping. it give the wood an extra way of staying together instead of coming apart.
now, if you want to test the glue vs glue and screws theory, the which one is best.
i suggest using compressed air on a pair of small enclosure, one with plain old glue and the other with glue and screws. but use the screws the right way.
you'll learn that the enclosure with the screws will actually hold more PSI, then the enclosure that was held together by glue alone. and is not because the glue gives up but because the wood gives. the extra clamping force of the screws is what make that combination of glue and screws much better.