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.
There are many nonsensical security rules in China (and in the US for that matter).
Glad you made it through without significant trouble.
I believe some/most flights to the US require a pre-flight "interview" (did you pack your own bags, etc) so that they can put a sticker on the back of your passport before they can give you a boarding pass.
I know some will do it at the gate while other airports do it before they give you your boarding passes. Perhaps this is why they didn't want to give you your pass since it would allow you to skip the "interview"..?
These 'interviews' happen variously before and after boarding pass issuance, and I don't believe mainland China is doing them as a prerequisite to BP.