[jraph]

> The things that are invalid should all have defined behaviour

100% agree.

And then I guess the philosophical question is "What's invalid when everything is defined?"

[chrismorgan]

The idea of almost all of HTML’s errors (parsing and conformance) is that they indicate likely errors (though it’s definitely quite possible to deliberately skirt the edges, e.g. content=width=device-width,initial-scale=1).