I guess both approaches have their "right to exist"
Mac's pen approach is mostly usefull if the base lineart
is kinda rough or too dirty/sketchy to get it cleaned nicely. It smoothes all curves to the users liking, giving it a bit more "press print" look.
Shadowfox' approach is great if the base lineart is already near perfection, where it's simply not needed to correct it or to smooth it out.
Nevertheless having the lineart "pen-traced" makes the picture infinitely scaleable due to the paths beeing vector curves. It's more work than running a tracing program over it, but definately provides the most accurate/controllable results.