IGH use a 3/32" or 1/8" thick cog .. the needs of a multispeed derailleur is thinner cogs.. and the more speeds = the thinner the chain.

& derailleur bushingless chains, by design, the roller edges are all that is contacting the flange pushed in by punching the holes in the inner link


a old style bushing chain there is a sleeve, that bushing, running the whole width of the inner link,
so the bearing surfaces for roller and pin .. are much larger.