going round the room in turn

Well if I was there I would correct their usage - what you got there, PAL, is a Sing-around (SAR) or a come-all-ye, or a folk club, or open stage. or a mixed session if they play "ensemble" occasionally.

Think jazz - "jam session", think "session musician" - hardly solo appearances are they?

Language is all about communication and it generates expectations. And disappointment if they are not met.

Pedantry has it's place and this is it.