EDIT:
To clarify. Who is going to be building their own rendering engine instead of taking an existing one - 3 of the 4 are open source - and building a browser on top?
But creating a rendering engine from scratch is hard and there is no business case for anyone doing it from scratch. Apple didn't (they tried with CyberDog ages ago) they used KHTML to create WebKit. Google didn't either, they started with WebKit. Opera gave up on their own rendering engine years ago.
Further, the W3C's argument historically has been to make the DOM easier to implement from the ground up (XHTML strict) compared to the overall rats nest of HTML5, which, as far as I'm aware, still is not fully supported anywhere [1] and is very loose about document structure errors etc. So, if you're planning to implement the W3C's DOM, it makes sense that you're agreeing at least somewhat with the W3C's historical philosophy about what the web should look like and how it should behave, so you're more likely to be concerned about the implementation difficulty of HTML5.
1a) Why would it matter that Microsoft, Google, Mozilla, and/or Apple object to W3C DOM 4.1 if they don't implement it?
1b) Why would Microsoft, Google, Mozilla, and/or Apple care enough to object to W3C DOM 4.1 if they aren't implementing it? Why would they even give any effort to a competing specification and just allow it to die from inactivity?
2) Why does what is in W3C DOM 4.1 matter if the high 90s percentage of users are served by a browser in the WHATWG DOM camp? This could probably be condensed down to "Why do W3C's specifications matter at all" really.
It matters to the utility of the W3C DOM spec that it doesn't represent either what browsers have implemented or what they will implement.
> Why would Microsoft, Google, Mozilla, and/or Apple care enough to object to W3C DOM 4.1 if they aren't implementing it?
They care enough because they want the W3C, if it is going to write purported web standards, to do something that won't confuse developers and lead to browser vendors fielding complaints from developers who mistake useless W3C documents for something meaningful.
> Why would they even give any effort to a competing specification and just allow it to die from inactivity?
They don't want to have a competing specification, though they do not seem opposed to having a specification with a different focus but consistent with WHATWG to the degree dictate by the purpose.)
> Why does what is in W3C DOM 4.1 matter if the high 90s percentage of users are served by a browser in the WHATWG DOM camp?
The idea is not to have opposing camps, though if W3C insists on making it an opposing camps situation, thst becomes a real issue.
Once upon a time Microsoft had 90% of the browser’s market. We created web standards in order to prevent monopolies, such as the former IExplorer, from holding the market hostage. That’s the whole reason behind web standards.
And yes, they matter even with an IExplorer that has 90% market share, because governments can and do enforce adherence. That’s also the reason for why Microsoft came up with OOXML, ODF being a threat even with a tiny market share.
Governments are not going to force every major browser manufacturer to support a standard.
That's why W3C lost relevance.
HTML5, in large part, was created to do exactly the opposite -- formally set down in writing all the de facto quirks of HTML as actually used, parsed and rendered in the real world, instead of continuing to prescribe behaviors which didn't match observed reality.
We've got no ActiveX, so your claim is false. Mozilla actually could implement ActiveX. They refused to do so.
Also, lets not forget that IExplorer 6 had incompatibilities with the standard, including XMLHttpRequest, even though Microsoft invented it.
Just for the note: I did - https://sciter.com
It was not meant to render all possible pages from Wild World Web but it renders HTML5/CSS3 (some subsets but still).
But the thread is an interesting read.