I think that I catch the issue a bit.
When we look through a SLR or RF viewfinder, we are very much copyng the usual way we look - forwards.
But looking through a waist level finder, is in some methaphoric sense like positioning ourselves with our back towards the subject while holding a mirror to view the subject.
It's a kind of drastic departure from our usual way of looking (hence the vertigo) and this loss of balance opens a lot of opportunities.
This visual compositional opportunities may be partially found at the SLR/RF viewfinder, but the relatively small image we have there, makes it barely noticeable, while with the big TLR screen they become very obvious.
Now I feel happy about not selling unused gear. "Fiscally irresponsible"