I wonder why we see so many of these attempts at bringing html/css to native, while we (or at least I) see so few examples of the inverse.

I loved creating iOS apps with autolayout. Some parts of it were a bit frustrating, sure, but you could do things that were pretty hard with css. Why don't we see any lib for "make an app just as if you were making it for native, but now it runs on the web!"