This is what happened with HTML. At first the syntax was pretty simple, but the error-correcting parsing meant that invalid syntax became widespread. In order t

This is what happened with HTML. At first the syntax was pretty simple, but the error-correcting parsing meant that invalid syntax became widespread. In order to ensure compatibility between implementations the spec ended up having to specify the exact parsing of any form of incorrect HTML also. Now the parsing algorithm of HTML is incredibly complex: https://html.spec.whatwg.org/multipage/parsing.html https://html.spec.whatwg.org/multipage/parsing.html