You can bottom studs in the hole with loctite and take advantage of all the threads in the part you are fastening to. Also when tightening you are using steel nut on steel stud threads . Otherwise you are spinning the steel bolt into cast iron threads that eventually wear and let go. How good are those threads in your block? Can you measure how wore they are ?
Also if the bolt tightens up in the threads or bottoms out before the part is tight how would you know. Studs are a no brainer. For the same reason you use them on aluminum. Or use "threads inserts/helicoils" where a stud cannot be used,