The reason for hiring someone you know is because you presumably know them well enough to know that you can trust them and that they aren't a fake or otherwise incompetent. Even then, you can do an additional vetting for competence to give the decision more credibility. Plenty of vetting is possible, and recommended, even if you eliminate all candidates that you do not know at all.

If that leaves you with no candidates, only then does it become an either/or tradeoff. Don't conflate the plan A with the plan B.

> But does hiring for merit really makes sense at C level?

Aren't these the people running the company? So, yes?