In a world where you have too much data and users want to see slices of data, progressive enhancement fails to deliver a fast, pleasant, engaging user experience. In the case, where you have complex tools that help a user meet some end goal more quickly progressive enhancement falls short of providing the easy to use tools. The only case where this works in any way shape or form is when a site is submittable via simple forms and all data can be retrieved by visiting urls. Any, slightly more complicated use case fails to be delivered at any reasonable pace with any sort of reasonable performance. You know the kind of performance that wouldn't make your server side fall over.
This whole progressive enhancement thing is mired in decade old dogma. While progressive enhancement can work sometimes, it is NOT the only tool. We shouldn't wholesale prescribe solutions without knowing someone's problem.