It's valid if it's understood: it shouldn't be taken to mean, "Randomly press keys on a keyboard for ten-thousand hours and you'll produce masterful code" but rather "work passionately and carefully for ten-thousand hours, learn from the masters, seek to emulate and extend their genius, and after ten-thousand hours you might be getting somewhere".
Simply trying hard isn't enough. You have to be smart about how you try. That's what I was getting at with that.
I agree, the snake oil is selling this idea that you /must/ improve your weaknesses or you're invalidated.
On your last point: exactly. The takeaway is that it was a rather obvious point to make: people who are gifted in in a multivariate of disciplines will thrive; I doubt many will dispute that.