> I'm curious what "its own vision" was
Well, back in the late 90s it was all about ActiveX and integration with other Windows components and applications in order to shove all other browsers out of the marketplace, gain dominance over the web, and further bolster the Windows hegemony by doing so.
So, as one trivial example, you could export a Word document as a web page, open it up in IE and it would look great. But then you'd open it up in Netscape and you're left wondering "WTF?" because it looked terrible and the images were horribly degraded - intentionally degraded, as it turned out.
You'd open up the page source to figure out what was going on and you'd see a bunch of ActiveX crap for the images that would only work in IE. And, IIRC, the images themselves were BMPs, rather than JPEG or GIF (can't remember if PNG was supported at this point in any browser, but it certainly wasn't by IE or Office apps). So the images would look high quality in IE (and have massive file sizes, because BMP), whereas Netscape and other browsers didn't support ActiveX or BMP so they were just displayed as low-quality (IIRC) GIFs with extremely low colour depth. They could have displayed high quality images if they'd used a more suitable format, like JPEG, but they deliberately chose the most crappy image format, so that photos would look terrible in anything other than IE and people would think IE was a better browser as a result.
Once the EU's antitrust case against Microsoft gained pace, IE development really stalled, and that's when it stopped evolving. This was around the time of late IE4/early IE5 era. You'd be hard pressed to spot any substantive differences between IE5 (released in, what, 1999?) and IE6 (release, I think, in 2001). So then, fast forward to the 2010s and IE6 is still around all over the place: doesn't support PNG, doesn't support HTML5, doesn't support much of CSS, polyfills can only cover up so much, etc.
You had IE7, IE8, and IE9 as well, which were also dogshit (IE9 marginally less so), and didn't implement standards properly or had some MS-centric view of functionality implemented (old habits die hard, even though the battle was lost by that stage).
IE10 was starting to feel like Microsoft were taking web standards seriously, but still didn't support loads of recent APIs (Web Audio springs immediately to mind). Same with IE11: better but still too far off.
Edge was better again but caught in the middle: it still wasn't as good as Chrome and Firefox but now it had also removed all vestiges of IE support, for addins and suchlike, so it had alienated that crowd too.
And then Microsoft just sort of gave up: they moved Edge to Chromium which, at the time, I thought was a mistake and bad for the browser landscape and, no surprise, so it has turned out to be.
Now you have all the Chromium based browsers (including Brave), and Firefox (which is substantially funded via Google), and there aren't really any other mainstream capable browser engines out there. And, no surprise, Google are abusing their effective monopoly power because that's what effective monopolies always do.
Chrome actually is the new IE because with it Google are doing (much more successfully) what Microsoft tried to do with IE in the late 90s.