Curious about your view on a qualified take.
By "some of the smartest individuals..." - I mean that there is a rare bar for work and aptitude here in the last ~3 decades if you look at a set of technocrats or thinkers historically.
Right now population * access to quality nutrition * access to early childhood and later education * interested in law school in the US produces a funnel of thinkers (90k graduates/y with ~19 years education) that is larger than almost any that has existed previously.
As some points of reference - some estimates put Rome at its peak at ~70mm citizens, the Tang Dynasty at ~80mm - both with access to fewer of the above conditions for the bulk of citizens. The Qing dynasty can hang on population in this thought experiment at 450mm, but the ratio of nutrition and education access was considerably lower.
If you compare SCOTUS clerks to actual luminaries like Gauss, they compare very unfavorably, but as a group I do feel that they are "some of the smartest individuals at what they do" that we've seen.
Is it possible that your high accomplishment in the field has given you an overly pessimistic view of the skillset required by your peers?
Your insight on the topic is super interesting - my background is as someone who was admitted to an elite law school and chose to follow their programming hobby instead - this part "However, even the absolutely best situated candidates don't have a more than average shot at success at their SCOTUS clerkship application." - makes me think that while there is a lot of networking involved here, the attainment bar is also - incredibly, unreasonably high - to be within striking distance, even if the last mile is networking, grind, and luck.