In my experience a good traditional "singaround" (the topic of this thread)and which I am more familir with, is all about the singers and the songs they sing and has less to do about the skill of the musician who accompanied his/her song on guitar etc or if other musicians joined in to support (and sometimes ruin)a song - whatever key it is played in.

Regrettably, I have found in my experience, that some 'singarounds' planned, promoted and intended as 'singarounds', can end up as a tug-of-war/contest/competition between singers and musicians; with the musicians trying to take over.
Which can be a great shame and can ruin the session altogether.