To be fair, your point is stupid.
So it makes sense people ignored it.
It's harder to date if you're missing a limb, if you've got chronic bad odor, if you're last 7 exes are all jealous psychopaths, or the world is overrun by zombies.
The article isn't claiming you can be literally the most physically repulsive person on the planet, and still pull successful, well adjusted and sexy.
You can say, "I never see mismatched attractiveness couples." Till you're blue in the face.
But anyone with a semi decent social group has tons of examples of miss matched in attractiveness couples.
Come to Chicago and walk through Lincoln Park on a friday afternoon.
Plenty of 9 sets of six pack dudes with girls who are Gold Coast 7s and vice versa.