I see the author's point, but the thesis is linkbait that can't even vaguely be considered true for anyone that is building modern websites with IE6 support. I have lost some time to some of these bugs. However if you compare the amount of time lost to Firebug bugs and vs IE6 support, it's still heavily skewed to IE6. The fact is that not everyone can know every bug in IE6, and though it's not too hard to avoid the big well-known issues, you may end up cutting design and interactive features or write a lot of ugly workarounds to deliver comparatively simple features. Additionally there are many subtle issues which become exponentially difficult to debug and isolate because the environment is so utterly opaque (admittedly I haven't tried Microsoft's commercial tools which I've heard actually have some utility, but I'll be damned before I pay a Microsoft tax just to debug for their hopeless broken software).

Firebug bugs are easier to deal with because there is more information and controls with which to isolate bugs. I admit they can catch you off guard from time to time, but as someone who cut his teeth on javascript in 1995, CSS in the IE4/NS4 era, I can tell you that IE6 is the bigger albatross around your neck. It's disingenuous to claim otherwise.