I didn't say other superconductors were not useful. I was saying that one that can be used at higher, room temperature temps is at the very least a new, useful thing. That calling it "limited in usability" is odd when existing ceramic superconductors with considerably cooler temperature requirements are already useful?

Still technically in a lab for now, but eventually not: https://en.wikipedia.org/wiki/ARC_fusion_reactor

> ARC uses rare-earth barium copper oxide (REBCO) high-temperature superconductor magnets in place of copper wiring or conventional low-temperature superconductors. These magnets can be run at much higher field strengths, 23 T, roughly doubling the magnetic field on the plasma axis.

This will be sufficient as soon as you can find a way to market a smartphone that only works while standing in a freezer. There's a world of difference between "above the boiling point of liquid nitrogen" and "in a room that people can use consumer electronics in."