Unfortunately you're quite probably right, though like everything, there's a continuum from totally not appropriate to really not an issue..
For example, focussing fully on photography with both hands while flying the final stage of a bumpy approach, or attempting to circle 200ft above someone's house would I suspect be considered darwinian stupidity by most.. however, taking a couple of scenic shots with one hand whilst cruising at 8000ft on autopilot probably doesn't really constitute a significant deriliction of command duty..