Lax parsers made the modern web possible. New web pages with image tags, forms, and scripts were possible without breaking that page's parsing in older browsers.
(Heck, it could've been a generic SGML feature! "Unknown elements' contents are CDATA, unless they have this attribute in which case they're PCDATA, or this attribute in which case they're ignored" as a rule the DTD...)
But it didn't! The problem with being strict here is that every possible usage has to be pre-imagined and perfectly implemented. You're suggesting the original developers should have just made affordances for everything that will be added in the next 30 years. That's easy to say now. The first web browser was essentially just a hugely successful prototype.
And can you imagine having to type all your tags in upper-case? Yuck. :)
that's the whole problem indeed
Yeah bad example if you wanted to convince me it’s any good :-D
User agents must treat elements and attributes that they do not understand as semantically neutral; leaving them in the DOM (for DOM processors), and styling them according to CSS (for CSS processors), but not inferring any meaning from them. https://html.spec.whatwg.org/multipage/infrastructure.html#e...
This is unrelated to parsing - for example a XHTML parser will be strict and draconian in its parsing, but still process undefined tags and attributes as above.
Sloppy programming is not about enabling new syntax at all. That simile is not useful.