Inspector
Nyuck, Nyuck, Nyuck!
The grub screw does not touch the router bit so nothing gets marked. It tightens a clamp that grips the bit. As for the torque, there are torque screwdrivers that are used all the time by machinists to tighten carbide inserts in tool holders. If you aren't a fan there is no reason for you to get one. Lots of members make recommendations with the best of intentions for tools and accessories that suit them that might not suit someone else's way of working.
Pete
PS. I don't have a muscle chuck.
Pete
PS. I don't have a muscle chuck.