He really doesn’t need to be prime Houston Harden in Philly - at least not regularly. If he can stay healthy, play make at an elite level, play solid defense, score efficiently, and (occasionally) put up Houston Harden numbers when Embiid is out, then he would be well worth the contract for Philly. The problem is that those things aren’t really a guarantee - especially his availability and defense.
With that said, he’s still a big name that brings a lot of money to a franchise and is a high level player. He can probably get the contract he wants, but it likely will not be with a contending team. Harden will have to choose between ring chasing or cashing out. It seems like he’s trying to do both and he won’t be able to because he isn’t Houston Harden anymore.
You don’t need defense if you score more than your opponent.