I've never seen JSON used in a project of any size at all where we didn't end up trying to hack constraints and types on top of it with some ugly and gross thin

I've never seen JSON used in a project of any size at all where we didn't end up trying to hack constraints and types on top of it with some ugly and gross thing or another—looking at you, JSON Schema. The more parts of your stack you tighten up, the fewer errors you'll hit and the more flexibility you'll have to use less-strict tools when it really matters. That's true at all but maybe the smallest scale. Worrying about the costs of having to document what you intend in a way your machines can verify—I mean, shouldn't you be doing that anyway?—is baffling to me. You don't need anything like Google scale to see the benefits of it. It's basic communication AFAI am concerned.