The problem isn't that most managers don't understand the technical, it's that they try to pretend that they do. Effective managers have a difficult task - find competent people (depending on existing staff to evaluate competence), delegate the work, take the blame for failures, highlight the role of each staff member in the glory of success (which an effective delegator is well aware of). None of this involves understanding the technology except at a big picture level. These managers are as rare as software engineers that actually understand the technology at a deep level - but they do exist.