To put this a different way, think of the way we sometimes rate how attractive someone is.
"The Star System... from a different point of view"
A "10" is like a 5*. Not too many of them out there. And there's not gonna be a lot of disagreement.
A 4* is like someone we'd give an "8" or "9". A bit more agreement here than with those we rate lower, too. Some people may think a "9" is a "10" and some may think an "8" is more of a "7". Regardless, it's still not representing a big percentage of the population and we mostly agree that they're all really attractive.
Now, a 3*... that's a lot of people. Everyone we'd rate a "7" (which, as we covered, some will think is an "8") all the way down to a "4" (which some will see as a "3" or not think is even worth bothering to rate). There's a world of difference between a "7" and a "4". To Duff's point -- telling me a "4" and a "7" is the same or pretending to in order to fit your argument is total bull****.
When we get to 2*, we're talking the range from a "1" to a "3" and we really don't want to spend much time splitting those hairs. So we're going to miss some here that might just need to get a new haircut, some skin cream and a diet & exercise plan to transform into a "7" or "8" within a couple years of putting that work in.
Last, we have the 0* which are simply unrated and would be a "0" or "TBD" on our attractiveness scale. We haven't seen them ourselves, know that there's some interest in them, but we haven't gotten enough 2nd hand reports from people whose opinions we trust to make us throw out a 2* (1-3) or 3* (4-7) rating for completeness sake of our attractiveness database.