My own gelding, moves fine off of leg and seat, but sometimes for more advanced flatting, he needs a little extra. I own half inch knob spurs, and one inch knob spurs. I primarily just always use the half inch. That's all he really needs. I rarely have to actually touch the spur to him, but as long as he knows they're there, he moves off nicer.
He gets flat out spaztic with a crop.
So, spurs can be a touchy subject, and are very easy to mis-use but I don't look at a person with spurs on, and think their horse has issues.