According to the latest stream by @Saltypatra , the devs cannot come to a nice decision about treasure maps because huge piles of these maps will turn into piles of something useful, and it will give an instant advantage to older players (who collected many maps) over novices.
But this simple solution will just give 1000 gems to a player with 10k maps. Not very big piece of advantage, is it?
It can be not just gems, but glory, or gold, or mix of some resources. So people can simply sell all of their treasure maps, or hold some 50-100 for casual hunting.