In every company I've ever worked for, and any company I know these kinds of things about, the position of a CTO is a high-level managerial role, with lots and lots of budgeting strategizing communcating yadda yadda, so you had better have someone on that seat who is a good manager and good at high-level, big-picture thinking and good with people and a very strong communicator.
If you require that person to also be the most technical person in the room at all times, whew. Either that's a very tall order or recruiting/hiring needs work. More technical than that person who's spent a career getting absolutely ace in their niche? More technical than the data scientist who spends 8 hours a day digging really deep into bleeding edge neural networks?
I'm totally with you that a manager should be able to understand the thing they manage to a certain (not too shallow) depth, but you hire experts for a reason, and in ordinary circumstances, and in an ordinary IT department, a C-level manager should not strive to out-expert the experts under their purview. That kind of micromanagement/smartassery will just drive away the experts, and then you need a new CTO and new experts and maybe go bust.
Exception to the rule: If you're in a startup where the IT departmend consists of a CTO and one guy remoting in from Bulgaria who runs the servers and is really really cheap, you as the CTO actually should be the most technical person in the room. But once you hire the first actual expert, you should take a step back and get more big-picture-y.