At least there was a distinction between web of documents (WWW) and shipped apps with custom canvas. Rendering apps with web’s DOM is stupid. It makes websites a mess and relies on everyone using the same monoculture of browsers (like we now have Chromium, WebKit and Gecko, all nearly identical).
If browser does not support one feature (like CSS’s transform), the whole house of cards breaks. It’s like making ASCII art in notepad and then expecting everyone to use the same notepad app with the same font and style, to not break our art proportions.
We need to split web into websites and webapps, with webapps being browser dependent or full custom canvases and websites being immutable human-readable and editable format.
Yes, but this is not possible when having multiple browsers :). So this is the point, HTML, CSS, JS… all should obey standards, but websites should not expect that every part of the standard is implemented. Sites should not break if browser does not have one function for example.