If you needed safety bars to curl, I think the exercise has a poor risk to reward ratio. It's completely understandable to use them when squatting, but when curling?
It has very little use indeed. Bodybuilders are better off with a much lower weight wich they can rep for 25, and powerlifters mostly dont need to do curls. Only when you are totalling like 900+kg and you really need ways to get more response in the arms, then curls could make sense
Sarychev, Malanichev, Konstantinovs, Koklyaev i've seen do curls.
the first one has a bench over 320kg, and they all 4 deadlift at least 400kg.
and even then, when they did curls (sarychev with like 100kg for 8 reps) they were in yeans and regular shirt, not really taking it seriously
dem genetics