The point is one SOLO GENIUS took all of the tools available to them at that point in history and made something amazing.
By your logic we have to go back and say cavemen inventing fire are key contributors to the Linux kernel because fire was an important tool to the creation of civilization which was critical for the invention of operating systems.
I don't doubt the importance of taking ownership for your projects and having good taste, as opposed to design-by-committee. But I think you're overstating the degree to which they worked isolated from others. I think these examples you've given involve people with good taste (or call it vision) who said no to a lot of prevailing wisdom and yes to other ideas... but it wasn't literally "I'm going to go into my house for 5-10 years and emerge out with perfection". It's usually more iterative.
Also linux follows in the footsteps of minix and other closed source unix systems right out of Bell Labs, so it's not like he wasn't drawing on a larger body of work. Hard to say he was inventing a whole lot of new stuff as opposed to duplicating an existing refined design. And large parts of what he did write were eventually replaced by others (the scheduler has gone through several iterations now), so those pieces are at least collaborative.
The lone solo genius is a trope for an Ayn Rand novel, not achievement in real life.
The closest thing is a guy who has a mental illness (or should I say non-neurotypical?) and writes code by himself for himself. But I'm sure even he uses stack overflow ;)