Probably because the operating temperature is about 0 Kelvin.
Though you have got me wondering whether anyone has put a crumb of high temp superconductor in a smd resistor package yet and if so, for what purpose.
Off the top of my head, I could think of one use, which would be to trigger a transistor to switch on and off some high power superconducting circuit when the small bit of superconductor gets cold enough to start superconducting.