I would have thought that being a FA is primarily a physical job, not an intellectual one
FBN,
I take it from that comment that you've never been on board when any sort of issue/emergency has occurred in the cabin.
There's been several times over my career (and I haven't been around all that long either) where the quick-thinking and professionalism of the Cabin Crew has been the difference between a situation in the cabin ending well/being diffused and it escalating/ending badly.
In those times the age/experience of the Cabin crew has ranged from either ends of the 'age/experience' spectrum.