That's… not any different to the WHATWG. You can comment on GitHub issues there just fine too. (And you can't just join as an invited expert for the W3C, but even being an invited expert means relatively little in most groups.)
> The W3C was created by Tim Berners-Lee, if anyone should have a vote on how web standards are run, then the creator of the web should be one of the contenders for it.
Tim is scarcely involved in the W3C nowadays, and hasn't been for a long time. The fact he's in theory the Director (but in practice almost everything is done by W3C staff in the Director's name) means very, very little.
That's an appeal to an authority who isn't even present.