As an example, take "double margin bug" [1]. It cannot be explained by alternative standards.
I remember there were more bugs of this type, but can't google them quickly.
[1] https://css-tricks.com/ie-css-bugs-thatll-get-you-every-time...
So again on its initial release, IE6 was the best browser. Did it have bugs? You bet! Were those bugs as irritating as the ones in Netscape - well the XSL-T that was generating html for a site once put a p inside of an li and Netscape would blue screen my Windows machine 75% of the time when that happened, unfortunately it turns out you cannot do a quick CSS hack for that.
Apple seem to be better than most at accessibility features and have been since day one. It's a shame that the best in business for accessibility is a private company.
IE6 was the best for a long time, also it had
VML which it kept in place and didn't move on SVG for a looooonnnnnngggg time, because of course VML was integrated in office products as the vector markup format and probably because it was made in MS.
So they had a vision for a vector image markup, and that was what they did.
SMIL-like extensions to HTML, and the use of behaviors in css were also part of their "vision" https://www.jb51.net/shouce/dhtml/time2/time.html
visions, like ideas, are a dime a dozen - in a browser market it matters if your visions are standards because if not they break the web.
IE's visions were not standardized and not supported by other browsers, they tried to instead do an end run around standardization. Chrome is the new IE. Chrome removing JPEG XL seems a pretty good indicator of that.
Also Safari had advanced color profiles before the other browsers, Safari does better work on accessibility than the other browsers, if most web developers thinks Safari is the new IE and Chrome is great then I think they aren't paying more than superficial attention to things.