Not quite; you (or rather, third parties properly maintaining them) can define your own components (i.e. in `better-datalist.html`) that you would then be able

Not quite; you (or rather, third parties properly maintaining them) can define your own components (i.e. in `better-datalist.html`) that you would then be able to use. But yes, there are indeed a number of limitations with that approach that result in this not being a widespread practice yet. An alternative would have been if some of the remaining elements people need would have been standardised and implemented (consistently and widespread, of course, like other standards nowadays) by browsers, but that hasn't happened either. Which means we're still dependent on framework-specific, incomplete non-standard implementations.