there are definitely positives about html and being declarative for sure...at least in the beginning... but looking at the complex beasts that web browsers have become now (maintaining/optimizing js, decades of backwards compatibility etc) it seems in the end, only google and apple can fund them (microsoft throwing in the towel, mozillas recent cutbacks)... im not sure this is what we originally wanted from the web...

as you say though, self rendering pages would need an api to provide accessibility, and also html is much easier to grok than bytecodes (developer accessibility)

tradeoffs...