Larchman People have been abusing carry-on rules for years. Sooner or later there are consequences.
Frankly, as someone who’s flown on probably close to 1000 flights, half domestic, half international, I’ve always complained that they did it wrong when they started charging for checked baggage. It should have been $100-$200 for a carry on and free for the first checked bag - the airlines should have been pushing HARD to get you to check the luggage down below and only have the most desperate travelers take their bag in the cabin. That would open up gobs of room in the overhead for the few people that did need/want it, AND make loading and unloading the plane twice as fast without people jockying and shuffling trying to find the last available overhead bin. In a 3+3 seat configuration like the standard A320/737/etc, there is not enough room for 3 full size carry-ons in the space above each row - there’s only room for 2 at most on each side - that’s 4 spots for 6 people. If the plane is full 2 people are going to “spill over” into the next row with their carry-ons and it propagates from there down the plane.
Instead penalize the people who want the “easy on easy off convenient overhead” and make them pay out the butt for that convenience, and let everyone throw their first bag down below for free.