Taking a quote from somewhere else as a reply always risks the possibility that it doesn't quite fit what it is being used as a reply to.
The quote might not fit perfectly, but the insight does.
I was pointing out that the described competence level implies that a competent programmer must be in the top 0.5% of the candidates for the job, not the top 0.5% of all programmers in the world.
And the point of the quote is that this really doesn't say as much as you think. Hence why "99.5% of candidates fail the FizzBuzz test" isn't as implausible as on first glance.
What is something you used to believe, preferably something concrete with direct or implied predictions, that you now know was dead wrong. Was your belief rational given what you knew and could know back then, or was it irrational, and why?
Edit: I feel like some of these are getting a bit glib and political. Please try to explain what false assumptions or biases were underlying your beliefs - be introspective - this is LW after all.