It's a good point, but I think they touch on it a bit with the thread about user churn (which prompted WeWork to kick-out the company that published that analysis based upon some "happiness" clause violation...)

Is it "product-market fit" if the company is literally buying that growth? Or does it become true "fit" once you can monetize those users reliably?

Ex: I buy a butt-ton of Airpods, put them in glass cases, and give them out on a nice table outside my house - for free. If I go out of stock on my first day outside, does that indicate "product-market fit" for my glass cases? (Answer: not really)