I guess your reasoning makes sense, but obviously there are counter arguments:
> Compiling for older browsers seems ok. If we stop additions for this reason, we would essentially stagnate the whole ecosystem.
> Sure, JSX is not react specific. No arguments here, but we should be able to come up with some convention - maybe `h` function? maybe the jsx pragma comment?
> We've made sense of much more complicated mutually conflicting standards problems before... we just declare stuff to not work anymore... like marquee tag... and if it does not make sense sometime, we put in feature flags, or `use jsx` language pragma? maybe `use jsx 1.0`, `use jsx 2.0` ?
https://facebook.github.io/jsx/#prior-art