> will stumble under the right circumstances

Exactly. Not every task or goal fits every person equally well. A good leader understands this and does their best to find that fit.

But it is in my experience not considered okay to talk about this too openly because people get offended.

You wouldn’t ask your best engineer to lead a marketing campaign or your best marketer to design your servers. They’re smart and would figure something out eventually, but who gets the task matters.