At Shea Stadium they were piped through the baseball PA system and only had their 100 watt, full-stack speaker cabinets as their arsenal. Stacking multiple cabinets and custom PA/monitor systems were still a few years away.
Good point, but you’d think people would say “Shut up, stop screaming” and why didn’t the Beatles just simply stop playing until they were quite, that would have really sucked if you wanted to hear them.