There was a visible problem when Harden was at Nets. There was more than one player who got a leader character. And this was causing some conflicts in the team. Now he can play freely and lead his new team. And I'm expecting him to make a good duo with Embiid there. Harden would play as a point guard and Embiid would score like always. This would bring an extra power to Sixers. They are already doing very nice in the regular season and they can perform better than this in the playoffs like this.
Well, the trade has been done and it can't be altered anymore seems that was the Nets wanted in the first place since they let him go, let's assume that was the reason. Hope he do feel good and lead the Sixers to a ring this year if that was also Harden wanted, and hope as well that there wouldn't be conflict anymore in this leader character.
Embiid and Harden has altercations in the past during games but wishing them well that it's all over now and they moved on.