The long answer is it's absolutely everywhere in our codebases, with some code relying on catch-predicates, meaning we have to pull it out in exactly the right order else things will break in weird ways... and we haven't gotten around to tackling that yet.
I still use Bluebird library for things like property based promises resolutions and the map is a quick way to run only so many promises at a time instead of all of them or in series.
