I think the solution is to hire both, because there is also the Peter principle: "promoted to incompetence".

The professional managers should be in a deputy position to the promoted ICs. This way they can bring their skills and expertise in management and empower the promoted ICs who understand the business or problems deeply.

The professional managers can be pretty useful if they don't have people reporting to them and help with processes, compliance, planning, making presentations and excel tables and yet the capacity for damage will be limited as the promoted ICs will need approve anything.

DEC apparently had "administration" instead of management, implying it didn't rule but rather assist, but I don't know the exact details.