The elimination of the Bushing tube around the pin, part of the inner link assembly,
made the chain laterally more flexible for Derailleur drive trains,

But the surface to spread the wear over is reduced..

Bushingless chains create the equivalent surface for the roller and pin, to contact
from the Metal displaced to make the Hole, in the side plate, inner ones.


In single speed drivetrains. full bushing chain are a bit longer wearing.

but 3/32 of that type are uncommon, compared to the wider 1/8".