Curses can be launched against any and all potential targets that may come to mind for which there is animosity or a desired negative outcome. This always takes the perpetrator off of a divine path or moves them further away than they were previously, and so is ill-advised because there will not be, in the end, a gain for the perpetrator but only a loss. There may be some minor near-term satisfaction in seeing things turn for the worse for their enemy or desired target to be dragged down in some way, but in the end those same energies will rebound, returning to them like a heat-seeking missile and will be amplified by the sum total of all negativity that resulted from their action in the first instance, not only the harm they caused their target, but all the secondary and tertiary effects radiating outward to drag down friends, loved ones and others influenced by the suffering indirectly.
This is why the actions of a perpetrator are always done in ignorance of reality, because it would be unthinkable to anyone truly understanding the energies and the consequences of heading in that direction. The universe is designed to be self-correcting, and that includes what will be, in effect, punishment for the perpetrator each and every time. The consequences meted out by society and its representatives, for example, the criminal justice system or simple social disapproval and potential ostracism of someone behaving badly, pale in comparison to the woes karma can bring.
Because the injuries are not necessarily transient and superficial, there may be deep soul wounds created by mounting high-level attacks against someone, and they can even persist from life to life once the person has been harmed. That creates a mounting burden of repayment owed by the perpetrator, and that is why you have been told the truism that the wind of karma becomes a whirlwind on its way back to the perpetrator.