I think it is more than that, the shower is a proper refuge where external stimuli is severely limited. Sounds are limited by the running water, temperature is controlled by the water, visuals are limited, and no one is generally barging in.
When I was studying math at University I had a remarkable number of eureka moments in the shower where suddenly infinity made sense. Smart phones didn't really exist then but showers still held power as a great place to think
This is why I switched to Graphene OS, it's much easier than I thought it would be!