It's On The Off Beat, Not Just Off The Beat
I wouldn't want to come across as some sort of misanthrope, because I like to keep that a secret. But there seems to be some sort of effect where the combined intelligence of any group of people numbering over 5, who are made to clap, suddenly plummets to that of custard.
I've been to quite a few performances where there'll be at least one song that goes well with some audience clapping; so the lead player does the over-head clap to get them started, the audience begin to clap:
and CLAP and CLAP and CLAP and CLAP AND CLAPCLAPCLAPCLPACLAPCLALWSIDJPIFOufhwe;iufh
the band quickly finish the song muttering, "effin' idiots," while they slowly gain a Messiah Complex.
Maybe it's something to do with crowd mentality and it's the same thing as when any wannabe dictator shouts a lot and the people throw themselves wholeheartedly into murdering their neighbours. A bit of an extreme comparison, but do you want to risk it?