That's nonsense. A CEO cannot be a jack-of-all-trades and has to lead a large organization and direct many people to do things that they, themselves, cannot do.

And scaling back, a manager of a cross-functional team is at a similar disadvantage. I work in a field where we mix ME, EE, CS/Software Engineering, IT/Ops, and other fields. A team could consist of people from all disciplines. Hell, right now I am learning the basics of astrodynamics so I can write the software related to it, the lead is an AE and can't code to save their life. They're still an effective leader.

In a previous team, the lead could not manage a Linux server, but still had sysadmins in the team. Did that make them an inherently bad leader? No, they deferred to the expertise of those team members. Like a good leader.