TCP/IP and HTML became dominant because they were open standards. Should they have been proprietary, they would have floundered and something else would have emerged instead.
When you have a long-running fork, especially one that is so active, merging it naturally becomes a nightmare. This is expected and ordinary.
The Linux kernel gets forked by Android vendors and others all the time. A lot of the changes never make it upstream, for various reasons. At least the story ends a bit better for KHTML / WebKit.
Anyone remember AppleTalk?
I'm beyond the point of negotiating with the people on this website. Apple is due in for exactly the same treatment, it's only a matter of time before the US eats their favorite crow.
But as an aside, don't let this site get to you too much. There's a lot of arguing for sport that goes on here.
I kinda doubt that. As soon as Microsoft had a virtual monopoly on the browser market, they let IE go stale for years. Hardly any feature development, hardly any bug squashing. Terrible security. By the time the browser choice thing in the EU and the antitrust thing in the US happened, the rot had already set in and everyone was fed up and yearning for a browser that didn't suck. Google drove their Chrome truck right into that gap.
If IE had actually been a decent browser, no amount of "choose your browser" screens would have been enough to sway people from it. Just like they cling to Chrome now because Google is too smart to make that mistake.
PS FWIW I don't like and hardly use chrome but technically as a browser it's great, I just don't like Google's attitude to privacy.