On my derailleur/disc bikes;flip bike upside-down,pop QR,remove wheel. No IGH hub is that simple.
R'off, external shift box, part of Disc brake setup, ads 1 knob to turn to disconnect the EX box from the hub.
Cassettes have gaps between the cogs to fill with crud after a bit of time in service,
single cog is easier to clean that user collection of dirt , mud and old chain oil, up.