Ultimately it comes down to the resources to create such a thing, right? There have been some successes with crowdsourced validations such as Facebook's translation efforts (although I think in that case it was merely a component of the process). And it would rely on a volume of edits that OSM may not have. There may be 1000 people ready to verify the location of the Statue of Liberty, but probably not the location of every building in a remote area being mapped for HOT.

Mapbox has built the start of a validation framework, and they have done very cool stuff. Of course then they get criticized for "forking" OSM. There are definitely valid criticisms there, but it seems like there's no way to win.