Why? They need to understand enough software at a high level to be able to manage, instead of turning lower-level details into management problems.
But, they also need to find software development frustrating enough that they are happy to not have to do it every day.
Best managers I met had almost nil technical knowledge or if they did they were not advertising it very much. They were gardeners. They made sure you were occupied, you provided value, you did what you liked and all projects that needed staff were allocated staff. They will meet with you every week for mandatory half an hour 1:1 chat to make sure everything is heading in the right direction and have general sense of how happy you are and how happy others are about you. If the manager thinks you are doing well that's about how much supervision you are getting.
I like this style A LOT.
Or perhaps PMing (which in many scenarios can lead to better pay, and less prone to ageism, though arguably even more stressful than being a manager)
I’m mulling these potential paths myself, to climb the pay scale and fend off ageism.
My sampling space isn't large enough, but it's interesting to keep an eye on the personalities of the managers in your organization from that perspective.
I mean that only half jokingly. One of the reasons I like to work at smaller organizations these days is the pervasive belief in larger orgs that somebody has to fall into one of two categories. This is often rationalized as a way to identify strengths, however more often than not IMHO it's due to insecurity in ones own deficits.
In reality, you can be good at both and like both and switch between them. You might have a preference and still be reasonably good at both. You might decide one is weakness and put effort into learning it overcoming initial dislike.