There's certainly part of that, but there's also likely selection/sample bias. The better the programmer, the less time they probably spend in interviews. And the "reward" on passing a programming interview if you're marginal is quite high, depending on your alternative choices of employment.

(Top tier Ivy League university acceptance rate is 3-10%, so if you're looking for someone of at least that caliber among the general population (or even among developers), an 80% rejection rate might not be crazy. FAANG (or its ilk) are the "Ivy League" of Software Development jobs)