I'm curious, do you think Ousterhout or the people quoting him are confused about this?
I'm with the commenter (here) who said that real life is more likely to be an initial-value-dependent or path-dependent PDE. Someone else said having a high-IV person on your team will raise the slopes of everyone else which seems also right: the issues are multidimensional, not affine 1-D.
Ousterhout is taking sides (smarter > more experienced) which is fine; he can make that argument. But using y=mx+b as x→∞ doesn't count as an argument; it's rhetorical flair, not rhetorical substance. The substance of his reasoning seems to be "That's my opinion based on my experience in my past jobs".
He does riff back on it, but it's five minutes of perspective tossed at teenagers, not anything formal.
I don't think anyone took this beyond the anecdotal evidence provided. We can argue motive and hypotheticals all day but the fact remains that this is just a blurb thrown at fresh undergraduates.
It's a motivational speech (delivered via heresay on Quora) not a thesis.