I think you're thinking of J++ (Microsoft's version of Java, not JavaScript). Now JScript (Microsoft's version of ECMAScript) does have some minor differences in the dialect, but that was only because the ECMA standard was at a standstill back then. Mozilla had no problems extending their implementation to match either.
J++ was created to counter shortcomings in the design of early Java language versions that Sun was not keen to re-integrate back into the Java language. That itself isn't bad (as other JVM-compatible languages exist, like Scala and Groovy) except that J++ then needed Microsoft's own Java VM with its own platform-specific runtime extensions - and that's what the Sun lawsuit was about. I agree it was badly handled by Microsoft, and in the end Microsoft just ditched Java and reinvented J++ as C# and the .NET Framework - which is where we are today.
As for JScript: before JavaScript was standardised there were extensions being added by everyone (Netscape had their own, as did Microsoft). I think Microsoft extended JScript in a very conservative way: the main change is the addition of the `new ActiveXObject` wrapper for COM objects which made AJAX possible, and also made JScript useful for automating Windows (and server-side JavaScript with ASP/JScript predates Node.js by 13 years!) - to my knowledge JScript itself didn't add any syntactical changes and provided you didn't use ActiveXObject your code would run without issue in other JavaScript engines. Note that this isn't the same thing as DOM extensions in Internet Explorer, of which there were many.
I think it's worth pointing out that when IE6 was released in 2001 it was by-far, the most W3C-compliant web-browser in existence: for CSS2.1, Netscape's then compliance level was abyssal, and even beating out Opera at the time too.
The only reason we are where we are today is because there's much less of a single dominant player in the browser space, so using standards are incentivized.
P.S. Yes, MS got their market share through shipping the browser with the OS. While it may have led to a monopoly in the browser space (or close to a monopoly, depending on how you want to look at it), I think it's hard to say any one of us wouldn't have made the same decision to bundle them were we in the position of selling the OS and also putting out a browser.
So, no, it's not like any Linux distribution bundling a third-party browser like Firefox or Chromium, since none of those distributions have a monopoly to leverage to start with.
Surely, you'll at least need a decent web browser to get online to download a different browser of your choice, no?
Go to store, by a CD with browser, install. The age when boxed software was a major thing extended past the point when IE started bundling IE.
Of course, with a TCP/IP stack you can get software from the internet a lot of ways without a web browser, too. FTP was a thing, after all.
If you just bought your first computer at that time, you weren't likely to have internet service to connect it to until you bought that separately, and when you did, you would have software, too.
[1] Although admittedly the last real work I did in Windows was 7, so please correct me if the situation has changed.
I'm pretty sure I've seen the dialog in Windows 10 as well, but not for Edge, which I find even worse than IE.
https://developer.microsoft.com/en-us/microsoft-edge/platfor...
The short version is that the actions of a non-monopolist are looked at very differently than the actions of a monopolist.
Additionally, you're dead wrong about "every Linux distribution", and even if you weren't, the fact that there are many of them would moot an antitrust argument.