In some ways they do, but actually going out into nature, smell different air, get aun on your skin, wind through your hair, see all around and not just a flickering screen and interface with reality with your whole body, not just eyes staring to a square and hands moving mouse and keyboard .. seems even more beneficial in activating the neurological system in the body.

They probably are, but only if you try new games, new maps, new strategies constantly - anything to get your brain plasticity working. Killing monsters in Diablo for 10 years in a row probably hastens the decline if anything.