Because software actually is kind of hard, and to get anywhere you need to convince a somewhat larger group than one to all work towards the same goal.
And how do you know he is not?
And how do you know he is not?
I don't see that mentioned in the article; a mention or a least a link to your own work would be helpful.
I don't think this is true. For example, Linus Torvalds didn't convince a larger group to work on Linux first, and then build it; he built Linux first and then the larger group came to it because they saw that it was worth working on.
Granted, Linux was not as ambitious as the kind of thing the article is talking about; but that doesn't mean the method has to be different. Working code, even if it's for a very small subset of what you eventually want to build, is a great convincer.