True ninja-rockstar engineers are professionals that don't exhibit the traits described.
The senior engineer described resembles more of the diva who is actually rarely that good, because he cares too much about his ego to question himself and progress.
Doesn't someone who can do 10x-20x the work of an average employee deserve a bit of an ego boost from time to time?
And that's if the "average" employee can do the work at all.
I've pulled so many "average" developers' nether regions out of the fire when they've gotten stuck that I've lost count. I don't care what term is used, but it's nice when the term actually describes the discrepancy between my performance and most developers.
Ninja-rockstar will do nicely, thank you. ;p
Seriously, though, MANY high-end developers in the start-up space are probably on the 10x-20x end of the spectrum. At least at the successful start-ups.
I'm sure there are exceptions for when the start-up is more about pushing data around in a mundane but novel way, and where the primary business value is NOT technically challenging. But even in those cases when the company scales it often has a problem, because the developers haven't done things optimally, and once you're already having scaling issues it's really hard to rearchitect everything to work better without messing up the existing site. YMMV.
The senior engineer described resembles more of the diva who is actually rarely that good, because he cares too much about his ego to question himself and progress.