Now all derailleur chains are bushingless in design. rather than a sleeve running across the whole inner link, supporting the roller and the pin.

the surfaces bearing the load are steel, left, pushed in , when punching the hole in the inner link . its how they are made more laterally flexible..

But the surface area is less , so the weight , being the same is spread over less surface and so will wear faster
than say a 3/32" Bushing Chain (running in a straight line )

but Derailleur shifting performance requires the flexibility.