teaching correctly banked turns to a novice is easier if you have a T/S to show
I don't think so, personally but that's not relevant to this discussion. Blind flying instruments are only a safety feature if the pilot is trained in their use. If cloud flying isn't legal then that would only be simulator training. You could argue that it was good enough but I would respectfully disagree. Proper training in cloud flying is an excellent thing, but no simulator available to a glidng club gives much idea of what its like inside a turbulent cloud. It's rough, wet, and can be thoroughly unpleasant. It's nothing like cruising a Pa28 between VORs or even flying a hold then an ILS. Speed limiting airbrakes make it less hairy, but these guys were flying a ridge, which put them pretty close to the terrain. Not a good place to go into cloud. More emphasis on not getting blown back into the sink would have been useful. The cloud certainly added another problem, but I suspect even without that they would have been struggling.