We already see that a little bit. JSON in theory allows arbitrary decimal numbers, but in practice it’s almost always limited to numbers that are representable as an IEEE-754 double. It used to allow UTF-16 and UTF-32, but in practice only UTF-8 was widely accepted, and that eventually got reflected in the spec.

I’m sure you’re right. If even this simple spec exceeded what people would actually use as a real standard, surely anything beyond that would also be left by the wayside.