I'm only half-buying this, because social interactions are clearly important, a lot of our brain is involved processing it, so if you don't exercise those parts

I'm only half-buying this, because social interactions are clearly important, a lot of our brain is involved processing it, so if you don't exercise those parts there must be consequences. The question really is whether doing something else with your brain is a viable substitute, and also exactly what works as social interaction for your brain. If you are on HN you would believe that all studies are wrong due to trivial sample issues, but the researchers are usually aware of the issues and try to control for it. For your analogous study nobody would mistake the cause for the effect like that.