Exactly. Not having an alternative marketplace--and no other one exists--is anti-customer and yet, you seem to have no problem with a Steam monopoly. Why?
"it exists" is not enough reason to use something.
If I start an online store that charges twice as much as Steam and has none of the features are you going to purchase from it just because It'S cOmPeTiTioN tO StEaM's MoNoPoLy?