1. When someone "successful" criticizes Gladwell's thesis, it's suspicious because maybe they just don't want to hear that they weren't really smarter than everyone else.
2. When someone "unsuccessful" criticizes Gladwell's thesis, it's suspicious because maybe they just don't want to hear that their lack of success simply shows that they didn't work hard enough.
#1 is your argument; presumably you find it plausible. It seems to me that #2 is about equal in plausibility to #1; and #1+#2 would say that anyone should be viewed with suspicion, as probably motivated by something other than honest intellectual inquiry, if they criticize Gladwell's book. Which seems ... unhelpful.
It also seems curious that you describe someone as (a) "the number one anecdotal blowhard" and (b) "one of my heroes". Why should the rest of us take any notice of someone who knowingly takes an anecdotal blowhard as a hero?
So people like 37signals had a good pinch of luck thrown in their pot, but Joel, I believe, actually got to the top rung of the internet food chain by persistence and hard work.
... and thus... Squeezed Books :-)
So bottom line, he really flatters successful people on the surface, while making the successful folk equal to the rest of us.
I don't think you are "mad" at Gladwell. I just think the motivation is strong and possibly an unconscious aversion to accepting that your success may be in huge part due to luck.
But then. Take with a huge grain of salt some asshole spouting off on a forum.
Believe it or not, you are one of my heroes, and I never seriously expected YOU of all people to be reading this.
Cheers to you and don't stop doing what you do. We are a better field because of it.