If a leader doesn't understand the underlying role (at least somewhat) - they can't reason about it. The best people managers I had were good at that skill and took it seriously, but also had a technical understanding of the role.

I think it's relatively common for bad people to get hired to these management roles because the skill can be harder to evaluate than straight engineering. Hire enough of this kind of person and your company dies. It's also why managers get a bad reputation generally - good managers/team leads are excellent, bad ones are neutral at best.