My preference is to have ONE color implement. I like them to be the same color as each other because I tend to touch up the paint to prevent, or at least minimize rust.
Does it have to be orange? No. In fact I don't have any orange implements. My box blade is tan. My H.D. scraper blade is blue. The L.D. scraper blade I just got rid of was blue, but it started out black & rusty before I took a grinder to the rust. My finish mower was Befco Orange/Red. . . but faded so last fall I stripped and painted it blue to match the scraper blades. My PHD is red. It needs to be touched up as it is usually left outside and showing premature signs of wear & tear, so that will become blue when it comes time to strip it down and paint it.
Why blue? Because that was what I had in my cabinet and it is easy to find Ford Blue paint just about anywhere. The same can be said about J.D. Green paint. Even the supermarket has Ford Blue and J.D. Green paint.