That's an unfair characterization. WHATWG doesn't version the spec like W3C did, but it's no less backwards compatible. See their FAQ [1], or just load the 1996 Space Jam site [2] in your modern browser.

[1]: https://whatwg.org/faq#change-at-any-time

[2]: https://www.spacejam.com/1996/

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mananaysiempre 3 days ago | parent [-]

Thus far, WHATWG has mostly behaved benevolently, true. But because they have stayed benevolent for now doesn’t mean we’re going to be any less at their mercy the moment they decide not to. As the recent XSLT discussion aptly demonstrates, both browser vendors and unaffiliated people are quite willing to do the “pay up or shut up” thing for old features, which is of course completely antithetical to backwards compatibility.

	▲	robocat 2 days ago \| parent [-]
		> XSLT Very rarely used, so two better examples: * http:// Now mostly unusable. * Quirks mode Netscape navigator or Internet Explorer compatibility (no <!doctype html>). Still supported by browsers for rendering old pages. Must be annoying to maintain. https://developer.mozilla.org/en-US/docs/Web/HTML/Guides/Qui...