The 76ers need a consistent 20 a game player next to Maxey. I believe in Embiid to be a good playoff secondary or 3rd option for this team but they need someone to help Maxey on the regular-season and this trade lets Embiid focus on getting playoff ready. MPJ is a great fit next to all the young talented players and he could fit the Maxey timeline for a while. They aren't giving up too much either, but enough to make the Nets happy.
The Nets give PG a place to get healthy and all the runway he needs to show off if he still has it or not. He plays out the 25-26 season with the Nets, then in the 26 offseason he can decide if he want to take a massive paycut to go play with a different team or he can get paid to be a very expensive vet and he can see if he wants to enter a coaching role eventually. If PG wants to go play somewhere other then the Nets, trading him would be nearly unfeasible, so he would have to leave 20-30 million on the table to get the buyout as the Nets have no reason to take a buyout that could harm them so if he wanted to leave he would have to sacrifice a lot of money, but in the 26 offseason he could go play for the Lakers finally if he wanted to.