The author is conflating two different things here. At large enough scale, almost everyone in a given role is practically interchangeable but there are some pe

The author is conflating two different things here. At large enough scale, almost everyone in a given role is practically interchangeable but there are some people who very much aren't. It's a hard leadership problem to both solve for making 99% of the staff function at a consistently high level while still carving out the exceptions for the 1% that really can move the needle at the company scale. At a the level of a single team, nobody is interchangeable, but both reducing specialization and creating a "we're all in this together" spirit are both important goals for long term team performance (and so people can go on vacation). Both of those problems have different solutions but can feel pretty similar when you're at the receiving end.