It doesn't have to be at the top.well, I can only speak from my point of view. I am not in anybody else's head.
problem is, that if you do not make new feats at the top of the power curve, they will be glanced over and ignored by 90% of the players.
And if you are designing a feat for 10% of the player base, you are wasting your time.
A feat that makes, say, greatswords not as good but still closer to polearms, doesn't have to be as good as PAM.
Of course, if it is way worse, it ends up closing off that design direction. If it is only a bit worse, it becomes a viable alternative. If it is usually worse, but sometimes better, it doesn't generate significant power creep and isn't a trap option.