Counterpoint:
Hills exist, go down them.
Like, the whole point of these things, at lesst as I see them, is that you get that free lunch on the way down a hill, then when going up a hill, well yeah, you still aren't gonna like, be 1:1 be able to power right back up it, but it will be easier going up that hill than if you did not have your free energy lunch on the way down.
This then results in you not needing to expend as many literal calories going up a hill, so now, you don't need as much food to recharge after a ride, thus you do actually on net come away with at least a portion of a 'free lunch', in that you don't need as much food.
But yes, I will give you that... the overall weight added to the bike from the batteries would have to be in a manageable range, so that the uphill assistance is not just entirely used on uh, pulling its own weight.