Wait! That means, if the only person using your product is your mom, you have PMF.
Based on what you said and the TFA, this is Superhuman’s PMF approach (i.e., perversely satisfy this metric by filtering users).
I don’t understand where this “engine” is, but perhaps that’s it.
That is - you don’t want to build for people that already love your product (it’s already great for them!) and you don’t want to build for people that absolutely don’t like your product (would need a very different product), but instead build for people that you can convert from “somewhat like” to “love”.
> Wait! That means, if the only person using your product is your mom, you have PMF.
This just seems straightforwardly correct. If you want to find the size of your total addressable market, use a different tool; this one is for product market fit.
They emailed me when features I mentioned were added and then a couple of years ago tried again. Been using it everyday since then as my primary email driver at work.
They know they have a niche product - a paid email client; an expensive one at that! So they filter so word of mouth and reviews and all match expectations and make sure their product is a good fit. It has been the opposite of scammy.