I'm not sure that applies say to a session of Irish jigs and reels. I'll agree they don't always need to be played as fast as they sometimes are but a comfortable pace, and indeed a dancable pace, is often out of the reach of a beginner. One wouldn't on a regular basis be say playing a reel so slowly that it no longer made sense in its proper context would one?

Les, not a beginners one but an any can join in a folk club and tried to cater for all (the pace really varied depending on who was joining in) started when we formed the Conwy Folk Club. I think it was mostly an accident as a few like me liked playing tunes. It seemed to continue and later became "official" with tunes in the break as well. I assume it continues.