The argument is a relative one. It isn't that these mid-level person and high-level intelligence people aren't quite different in many ways ... it is that relative to non-human standards of intelligence, they are likely relatively close (say within an order of magnitude of capability).
Why does it matter how it compares to some x10M performance difference that exists somewhere? The individual output of two people can still hugely differ, which is what this discussion was about, no?
The claim was that someone would be not just very slow but completely incapable of completing a task even given an arbitrary amount of time. That would mean there’s some kind of fundamental difference between the two people, which is just a ridiculous claim. What one person can accomplish in three years can almost certainly be accomplished by another in ten provided they are in the same profession and competent.
Again, let’s assume 50%ile, not “competent enough to complete the task.” Though realistically, I would bet Hacker News commenters skew higher than 50%.
Here is a much better summary of the argument:
https://aiimpacts.org/is-the-range-of-human-intelligence-sma...