I think overkneading may be a myth in anything but a commercial mixer or food processor.
Peter Reinhart in BBA agrees with you. I do as well unless you are talking pizza skins then all bets are off.
Good topic of discussion.
It's difficult to overknead bread when you're kneading by hand, fatigue usually wins before overkneading is achieved, but bread dough can be overkneaded which results in a tough and chewy texture which might not be all that objectionable for bread but for biscuits and other lighter breads it is not a good thing.