What exactly is the utility of the above quote of yours then?

To show that the correlation is spurious at best.

Has it become even more successful after he’s mellowed out?

Yes, it has. Usage of Linux has been growing over the years.

My point is exactly that. It’s not obvious, and as such you can’t attribute the success of Linux to his behaviour. Like the OP said, there’s no logic in looking at something successful and picking a singular thing to be responsible.

How is that obvious? Especially because it’s become even more successful after he’s mellowed out?

The analogy is that the end result doesn’t justify the behaviour from the person in power. It’s apt.

But did it work because of the style or in spite of it? No reason to believe it wouldn’t be even more successful if he had been less abrasive like he is now.

It’s not a comparison, it’s an analogy. Important distinction.