Great they share specific metrics and give a sense of how they evaluate companies, although all First Round articles have this tendency to be so overdesigned it takes away from the content. The discussion on Lenny's podcast is easier to digest: https://www.youtube.com/watch?v=yc1Uwhfxacs

I think the 4 P's is a valuable framework for getting to PMF: Persona, Problem, Promise (Pitch), and Product. Usually startups that don't work have a fundamental problem with a few of these (they try to solve too many problems for too many people in a subpar way - i.e. they don't have a strong answer to: which problem are you solving, for who and why it is better than alternatives?). Startups that are willing to iterate over the 4 Ps have a shot at getting to PMF, those that don't usually will struggle and then die.