Some experts see Simmons as a problem, so he can't keep proving in a team that does not anymore appreciate him.
Embiid is very effective, and he is truly a star, but if he doesn't have an attitude of a real team captain, this team will still face struggle even in the long run.
Embiid is indeed very effective with his role in 76ers and you're right he needs to step up and be an effective team captain as well. Maybe If they could replace Simons with a more effective player than him, they'll probably have a shot at the conference finals.
I guess the play is more so focus on Embiid, they have a lot of talented players like Tobias Harris as well who should constantly attack, but his contribution is still not enough to take over when Embiid is struggling. The problem with the style is that Embiid will eventually gas out in the 4th quarter, and it would be easy for the opposite team to have a run as they have a better team work, and we have seen that during the Hawks vs 76ers series.