The crazy thing is watching Harden now in Philly, he's almost fully transitioned to being a facilitator rather than the primary scorer he was before. This full time playmaker thing really suits him, I have to say. He does still iso sometimes to get his own shots off, but off the ball I've seen him provide screens and cut a lot more than I ever saw him do in Houston.
So maybe it's not a question of whether they can do it, it's about whether they want to. When Harden and Russ were both in Houston, they used to take turns in bringing the ball up and when one is doing it, the other would just stand around looking useless completely uninvolved, but it's a completely different Harden we're seeing now in Philly.