It's named that for a reason. It has to do with invariance under an arbitrary selection of parameters like scale, hence, choice of railroad gauge.
At least they tried to give a descriptive name! Most ideas are named after the people who are most closely associated with them. Yang-Mills. Newtonian. Euclidean. Planck. Many of those names invoke very specific ideas, even though eponyms are about as opaque as they come.
Just as you can select whatever railroad gauge as a country (if you also build compatible trains, obviously) and have it work just fine no matter what you select--until you try to connect it to another country and then you need to have converters--, some physical theories have gauges like this that you can choose however you want and it will work fine (and be equivalent to a theory in any other gauge)--but if you want the theory to work with the next guy's theory you have to have converters.
I always wished they gave this thing a better name but I have no idea what.