Microsoft tried that, investing in easier to use GitHub tooling to allow a wide range of people to submit pull requests to update/fix bugs in the W3C HTML standard. "If you build the field of dreams, they will come...." Nope. "They" had all gone to WHATWG ballpark, and all the W3C editors do is cherrypick (that's the actual word in the HTML 5.2 Recommendation) WHATWG's specs. It made a LOT more sense to just join WHATWG for HTML (and DOM).
> > The W3C actually does do some good work in other working groups
Right, W3C as a whole does a lot of good work. CSS is a good example, Web Payments, Web Authentication, Web Assembly come to mind as groups where a broad group really does come together and build consensus on how to solve hard problems. The HTML and DOM communities, however, have moved to WHATWG for reasons that happened long ago and apparently can't be un-done, even if a company with Microsoft's resources tries.