They're very far from irrelevant, depends on what kind of Web development you do, I would say -- I have been writing WebAssembly by hand (I mean, a lot can be said about that but it's a thing) and the spec. is authored by W3C. There's plenty of other things they author, like, you know, either one of the many _CSS_-related specifications.
It's just that with the modern Web 7.0 (or whatever version we're on now), it's WHATWG that's most prominent since there's that one spec that defines 90% of what happens on the Web, it's called "The HTML standard" or some such. Then you have Google de-facto authoring specs., which may or may not find their way back into the HTML document, but even if they don't, they do make you feel like W3C is left behind.
It's just that with the modern Web 7.0 (or whatever version we're on now), it's WHATWG that's most prominent since there's that one spec that defines 90% of what happens on the Web, it's called "The HTML standard" or some such. Then you have Google de-facto authoring specs., which may or may not find their way back into the HTML document, but even if they don't, they do make you feel like W3C is left behind.