Face it- the airline employees don't want to deal with such things. They allow people on board who are so big they take up 2 seats and let the passenegr in the next seat deal with it. (See other threads here.) They frequently stand by and let passengers deal on their own when a family isn't seated together or someone is occupying the exit row or bulkhead seat you carefully reserved. Why should they police carry-ons when the passengers are willing to hoist each others' brick-filled bags into the overheads? (In fairness to the FAs on this one, I've heard they can't collect Workers' Comp if they strain their backs doing this because it's "not in their job description"- but why do the gate agents let it on board?)

As a 51-year old lady, I don't assist people who can't stuff their own bags into the bins- but I always make sure that I can handle my own without assistance.