if you didn’t know what you were getting, you’d default to an OC as HC.
It’s an offensive game.
Defensive coordinators frequently are adverse to the kind of offenses it takes today, and not all of them have their “Kiffin” moment.
And a really good OC is going to eventually leave, which means the defensive HC is going to always have to get the hire right every few years.
And offensive coordinators aren’t ask adverse to any particular type of defensive system.
Concern with an OC as HC is if they aren’t good, and now you’re stuck with the offense because he isn’t going to hire an OC. Like Napier at UF right now. Or Richt at the end, when he choose to quit rather than give up play calling duties.