Please do. One of the goals of writing the contemporary HTML spec was to make it easier to make a Web browser by actually defining all the difficult things that browsers have to do. (It used to be really hard to make a browser because literally half the work was reverse-engineering other browsers.)
I don't understand why this isn't solved, but even more so I don't understand why most people seem to be perfectly happy with the current state of things. In fact, I get the impressions most web developers like this. They like writing scripts to solve trivial problems or finding obscure scripts that do it for them. Makes them feel helpful and important, or something. Me? Makes me angry. This should have been conclusively solved a decade ago.
I'm seriously considering writing my own toy browser. Not that someone will use it, but at least I will be able to tell for sure how difficult is it to solve all these trivial problems.