if people are in folk clubs because they want to sing/play [and hopefully listen to others also], why would they want to pay to have less opportunity to do so, unless, perhaps, they are short on options ?. much has been said by those impatient with amateurs, but in fact, there are often performers at singarounds that [ imo] are often more talented than the paid performers. and as flora inferred ,some of those paid performers lack the grace to listen to others contributions. an organizer might want to have paid acts, but they might be better at a separate event....if they can make it pay .
and if a club wants to insist on a ban on music stands/books/sheets, they are entitled to do so, but I suspect that a decrease in attendees may result. you never know though, such an approach might corner the market of the confidant and elite performer !