I think there's a useful lesson here about precision in writing. _Why_ the Fog Creek developers left isn't central to the essay's main point, and it's not interesting in itself. But the author did include it, so clearly he thought it was relevant somehow, but why? One salient hypothesis, in this context, is definitely "they left because of Wasabi".
Well, I don't think they actually did leave because of Wasabi; the chain of reasoning I described above isn't very sound. But it's easy and obvious, and the author could have avoided it by doing a little less.
Sure. As I said, I don't think skepticism is _correct_ here. But a critical reader will always be asking themselves, "why did they write it that particular way?", so as an author you have to continually ask yourself the same question.
Well, I don't think they actually did leave because of Wasabi; the chain of reasoning I described above isn't very sound. But it's easy and obvious, and the author could have avoided it by doing a little less.