They use it as a substitute for egg whites in cocktails, and honestly it's better.

Damn I have been pouring my eggs down the drain this whole time

The reason you cook beans and traditionally throw away the water and foam is because you want to get rid of saponins - which aquafaba contains. Legume-eating traditional cultures carefully skimmed off this foam, so presumably because they learned it's not so good. Of course, a little is not so bad, presumably the plants evolved this as a pesticide. But there are other egg replacements like flax or chia seeds.