For web apps, IE6 and anything that came before was always terrible. It used to be hard to build a decent web app, even if most of your code ran on the server. There is a huge qualitative difference between building for an ad-hoc platform and one that is rigorously built and tested against some externally defined standard.
Sure, Chrome may be lagging in some areas, but--like all modern browsers--the platform it provides conforms rigorously to the standards it supports. And that makes all the difference.
My point is that in the IE6 era (and previously), doing so was categorically hard -- I didn't say impossible. Also, that changed with FF 3.5, IE8, Chrome, etc.
Admittedly, IE6 and FF 1.5 were the first browsers I had to develop apps for from scratch. (And FF was already far more robust.)
As far as divergence from the standards, again, that was generally not the case when IE6 shipped - if anything, it was at the bleeding edge, and past it in some ways. The real problem with it was that it wasn't updated fast enough to keep up with the rapid pace of web standards after the initial release; and when IE7 finally came, it had very minor improvements (IIRC the biggest one was PNG transparency?). But that was a different era already.
MS IE 1 was developed for Windows 95 Plus!, MS IE 2 for Windows NT 4.0, MS IE 3 was for Windows 95 OSR2 (essentially new OS, it even included it's own brand-new filesystem!), MS IE 4 was for Windows98 (but was rushed with Windows 95 OSR 2.5), MS IE 5.0 was for Windows 2000 (but was included as part of Windows 98 SE), MS IE 5.5 for was Windows ME (which wasn't initially planned - that's why it got 5.5 number, not 6), MS IE 6 was for Windows XP, MS IE 7 was for Windows Vista (and since Vista was horribly delayed so was MS IE 7) and MS IE 8 was for Window 7!
The first version of MS IE which wasn't developed as part of Windows development was actually MS IE 9.
Considering the context and era, IE being updated through Windows Updates was actually a huge improvement over the state of the art at the time.
