You might have a fair point regarding things like ActiveX which only work on Microsoft's own platform and serve to further lock-in to Windows. However, as was pointed out above, XMLHttpRequest is one such nonstandard feature that Microsoft introduced. How is that feature irresponsible and anticompetitive?
The feature is anticompetitive because it was part of a large-scale and well-documented effort within the company to coopt and/or destroy technologies not controlled by themselves. A handful of innovations (which would have happened anyway) that happened along the way do not justify that kind of behavior.
Either you're changing your argument or you failed to articulate your position initially. Nothing justifies Microsoft's abusive practices; that's a non sequitur.
If we take your original statement and change "browser" to "search engine" and "IE" to "Google", we end up with this: "If any single search engine had the marketshare that Google had in its heyday, it would be irresponsible and anticompetitive for them to implement nonstandard features."
If your initial argument was that an illegal monopolist should be unable to introduce any new features, that's an entirely different statement than saying that having a large marketshare means that any new features are irresponsible and anticompetitive.
>If we take your original statement and change "browser" to "search engine" and "IE" to "Google", we end up with this: "If any single search engine had the marketshare that Google had in its heyday, it would be irresponsible and anticompetitive for them to implement nonstandard features."
If Google made non-standard extensions to robots.txt, that would be an equivalently anticompetitive situation. To my knowledge Google hasn't done anything like that. We are not talking about just any features here, but features that make websites incompatible with other browsers. Search engines, by and large, are not concerned with interoperability in the first place, so your analogy is nonsensical.
