You know for all three years worth of people that the experience wasn't transformative? You know it didn't have an effect on opportunities or employability for these 3000 or so people? I doubt you know all these people that well.

But even if you do know all these people that well and are right about them your conclusion is still not supported. You criticize the author by assuming they are confusing correlation with causation. I suggest you analyze your own reasoning. You are engaged in flawed statistical reasoning and are committing a famous fallacy.

Even if you are absolutely correct about your own experience and the 30000 or so graduates that you know your conclusion could still be wrong. You need much better statistics, or provide evidence that your experience has always been the case for HBS.

I suspect that for a population of 80k with a relatively low variability, n=300 is more than enough.

One of us needs to brush up on their stats...

Indeed one does. One also needs to brush up on argumentative fallacies. It's quite bad to criticize the author's reasoning whilst yourself engaged in bad reasoning.

To be clear, your original post was mostly reasoning along the lines, "My experience was different therefore the author is wrong." And your second post didn't specify why you think your experience was normative. Merely that you think in a band of a few years you know how others benefitted or didn't from HBS. This is especially bad reasoning as the article talked about HBS influence over a much broader range of years.