In the first Fire Emblem for the NDS, if you lose too many allies you get sent to special optional maps with new exclusive characters available there
in theory this is pretty good, struggling units can get new powerful units and more experience than others (experience being finite)
In practice said players might still lose units in the new maps (they are not particularly easy as I recall) and end up worse than before. And good players who consult guides can kill off their worst units on purpose to get all the rewards with no real cost. I like the idea of Fire Emblem trying to make you accept permadeath, that was a bit weak but good effort IMO