10x developer is absolutely a thing, in the easily observed phenomenon that some developers are 10x more productive than other developers. The "other developers" are earning good wages and doing good work; the 10x developer is usually found making 2x or 3x the norm.
That said; I just can't believe that a team can perform 10x by the actions of one person. This claim is so outlandish I may just have to skim the article. It is often the case that having a 10x developer nearby can greatly improve the quality of a product, but that's not the same thing as improving the team.