Ya, I think it's probably true, Not going to say why, but it probably is. Now where the F/A confusion is part to blame by PSA and the FAA. The whole carry on fiasco is a change in W&B procedures a few years ago for carry ons. I.E. I've carried this on board before with no problems. Well here is the problem of having so many contract carriers. The change in the FAA W&B is that the smaller jets can agree to not allow the standard carry on's, and they get a break on passenger weights. Though they take a hit on the carry on weight, but overall it's a paperwork weight saving thing for the carrier. Hence why PSA flights, you must gate check anything larger than a pilots flight bag. When they first got the jets, it wasn't like this. Then they started bumping passengers and bags on wx days, and PSA opted to changed their carry on policy to the no carry on, gate checked policy. I think it allows them to carry an extra 2 or 3 people and bags on the 50 seaters.
So the only guidance they give the f/a's is, if it's bigger than a pilots flight bag, it gets yellow tagged. Now you ask 10 different f/a's why they have to, and they come up with 100 different reasons, normally none of them correct.
Bottom line.......blame should be put on Tempe ultimately. Not having a standard across all they contract carriers, in order to provide a seamless product no matter which one you fly on.
Wanted to add, it's even more confusing when you fly on republic, which has express on the side, but you can't get a bag gate checked like you do on express. Instead they follow ML policy, and extra bags are gate valeted, which use a different bag tag for that. Was even more confusing when republic was on the E gates. as outstations would sometimes bring up the yellow tagged bags off those planes, and other stations wouldn't, saying that bags weren't gate checked for those flights..........Clear as mud huh?