Not in my experience; there are all sorts of nooks and crannies that catch you out between those browsers (not that IE isn't worse of course :))
I seriously doubt one can innovate on the web, without using cross-browser hacks to only support the non-IE crowd. Even "standards" as simple as the DOM would have you jumping through hoops, but don't believe me... http://ejohn.org/blog/the-dom-is-a-mess/.
Or something as simple as .nodeName from the HTML 5 spec? http://ejohn.org/blog/nodename-case-sensitivity/
How about something as "simple" as border-radius? That's right, I can easily make a mess of every browser.
Google Mail, as a browser front-end, is only amazing by virtue of innovations made by Microsoft and very little to do with anything since. Little to do with "standards" of today. Faster than Outlook? No; how? Better? Sure, but only because it is more accessible to me. Nothing to do with ActiveX, or shall I pontificate how GMail sucks because Firefox is a hungry beast and crashes under its own weight? No, that would make zero sense.
I am looking to create good and fun websites and not sitting around to complain about how my job isn't made easy, because every browser has different levels of support. And believe me, I've been waiting a long time -- longer than you seem to grok -- for the W3C to "standardize" vector animation. Still waiting. Can't wait for the web to be free of these working groups and zealots.
Things are a lot better than they have been, things are getting better every year.
Flash filled -- fills -- a lot of gaps.
ECMA tried to make a splash with CLI.
Me? I stopped support of IE6, outside of what is easily hidden in libraries / wrappers, which means I can support almost everything still. As well, I use, support, and contribute to Chromium.
Now I can develop for Firefox, and know it is going to work in Safari, Opera, Chrome, etc... I know it is going to work on most mobile devices, TVs, and iPads.
We can do amazing things like Google Mail, which is still faster and better than Outlook. All these without having to worry about ActiveX crashing the browser.
I am not sure what you are looking at, maybe you are only interested in Flash games and vector animation.