As long as you understand where your team's talents are best deployed, a wider knowledge base of your product is only an advantage as a manager. To your point

As long as you understand where your team's talents are best deployed, a wider knowledge base of your product is only an advantage as a manager. To your point edw, yes when someone attempts to add value where they have no skill, frustration ensues. But, when you can better communicate with your team and understand their plights (via a knowledge of your tech), then expectations align and make for a better team workflow (emphasizing wccrawford's point).