You recall correctly that I am a natural, but my number doesn't fall outside of the range of a natural lifter according the FFMI. It's toward the top, yes, but there were examples in the data collected that went as high as the 27s.
We may be talking about different metrics in all honesty.
I don't see it as a scale that says "this is the absolute max" but more simply "Observing top levels of natural lifters, this is where the max tends to fall".
EDIT: I'll also say that I don't find it's conclusion about me wrong. I'm 30, been lifting since I was 14, and don't imagine I have a whole lot more muscle to put on at this rate. Probably eek out a few more pounds here and there, but definitely not going to be hitting a ripped 220 naturally.