A CSS reset primitive would have been a super nice addition about 20 years ago. :/
Web Components have solved all the problems the Dojo framework had, long after the web has forgotten what it was.
I agree with the problem of slot and template elements not solving the 1-N mapping and the forcing string representation for attributes (including the dataset attributes). It’s such an overlook, and it renders the Web Components API almost useless for any real world case. It’s a shame, though, as it would be great to have browser optimization for component rendering.