Thanks for your replies.

I wasn't able to print from the club because I was late for the boarding unfortunately.

I also noticed the reliance on paper boarding passes in PVG another way. Because our flight was severely delayed, I lost my paper boarding pass between clearing immigration and getting on the delayed flight (with the all-important red stamps on it). The PVG gate agents made me wait until being the last passenger to board, "because someone else may try to use your boarding pass".

I'm not really sure how me with my proof of identity passport, having been registered as boarded, would give someone else the opportunity to use my lost boarding pass... but I guess their rules are their rules.