>You can comment on GitHub issues there just fine too.

Yes, but (and you can disagree with me here) the W3C has much better international participation and say in standards. I know you can just file github comments, but none of the world has any real way to oppose any development that the whatwg makers have proposed. There doesn't seem to be any consensus forming or way to really oppose any development apart from filing a github issue. All the editors are pretty much from one company, which feels like handing over control of the web to that one company essentially.