Unrelated to pipes specifically but along the same lines, I feel like app developers ought to conform to a pre-defined standard like schema.org for their respective content so that everything can be inter-operable in theory. That way if I'm using Microsoft Todo or Google Keep or whatever, the potential for Google Assistant or Siri or Cortana to add to whichever Todo App I'm using is already there.

What are the drawbacks behind something like this?