I once spent a long time building a pretty detailed pro forma model to raise money for a brick and mortar business in a spreadsheet. It was beautifully formatted, comprehensive, and appeared convincing. I patted myself on the back for training myself as an investment banker in 3 months.
I showed it to an i-banker friend that I respected. He barely glanced at the spreadsheet, but offered one thing:
"It's not about how detailed your model is; the most important thing is what your assumptions are."
I was floored. No one cares about spreadsheets for a tech startup, but it turns out even when you're trying to get a brick & mortar, cashflow business off the ground, still no one cares about spreadsheets.
That's probably what folks are reacting to here: the author is ultimately making an point by taking a set of assumptions and using those to derive the point. It seems like the argument is about the assumptions, not the calculations.
In case anyone's curious, here's the model in question. It was for a ping pong social club with food & beverage in NYC:
Base model: https://www.dropbox.com/s/m8amviwttxsq09b/The%20Push%20BK%20...
Sensitivity analysis: https://www.dropbox.com/s/vcw1un7usubb5vb/Sensitivity%20Anal...