My issue is not the "rules" but the airline not enforcing them so they basically become "suggestions".

Two issues; 1)if they impose bag size "rules" then they should be enforced. If everyone expected it to be that way then they would comply.

2) Boarding groups. I have seen countless (and clueless) numbers of travelers just wander into group 1 or 2 boarding making believe they have no idea which is boarding..and most have group 4 of course. The attendants rarely call them out on it.
On one of my recent trip (I believe on Delta out of BOS) they had the passengers scan their boarding pass by boarding group...green if it was appropriate and red with a buzzer if not. The red group was sent back....

Perfect....