The problem is that there are so many ways to do things, and every website uses a different subset.

Need to layout your elements? Great, that's what flex is for. I mean grid. I mean float. I mean the position attribute. I mean tables. I mean the margin attribution.

I'm really looking forward to a better integration of Webassembly. Then we can each pick our own libraries for layout/colors/video etc., and writing a browser will be more like writing a VM than writing huge entire ecosystems.