[RainyDayTmrw]

It was new-ish, and it barely caught on, only in some digital camera lines for some brands (Nikon and Sony). If anything, plenty of prosumers were annoyed that they now had to buy new cards to use the second slot. The rollout was also bad. Some manufacturers thought they could get away with one slot only (Nikon Z6 mark I had only the single XQD slot, a precursor to CF Express Type B), owing to the improved reliability of CF Express as a form factor, but that was a bad idea, and didn't account for failures in the underlying flash or controller, and that annoyed actual pros.