The need for tourniquets is rare. At least outside of a war zone (or Chicago). When I was an ambulance paramedic, we could use tourniquets if we wanted, but I never had to. I never even considered using one. I was able to stop my patient's bleeding by other methods.

But if you need one, you need one. Doesn't matter if that scenario is rare - you need what you need when you need it.

I carry a tourniquet in my day bag, along with other first aid gear. I do not really expect to ever have to use it, but it's there just in case.