That’s a really good question, Corey! I was deliberately pretty hand-wavy there. On the one hand, experience really does matter; but on the other hand, different people level up at different rates. I would have a hard time believing someone with only 4 years of experience has the depth of experience to be a level-3 — most of the people I’ve seen in that cohort are much more seasoned.
What I really want to express here is: (1) experience matters, and (2) it’s totally normal for a software career to take a decade or more to unfold. As a manager, I want there to be an expectation that even good engineers don’t get a promotion every year. But yes, providing a hard arbitrary limit would be silly.