[lucideer]

> There's enormous non-xhtml legacy than nobody wanted to port.

This is a fair argument if content types were being enforced but XML parsing was opt-in (for precisely this reason).

> And tooling back in the day didn't make it easy to write correct xhtml.

True. And instead of developing such tooling, we decided to boil the ocean to get to the point where tooling today doesn't make it any easier to lint / verify / validate your HTML. Mainly because writing such tooling to a non-strict target like HTML is a million times harder than to a target with strict syntax.

A nice ideal would've been IDEs & CI with strict XHTML parsers & clients with fallbacks (e.g. what Chromium eventually implemented)