It's just the timing though, similar to what the Clippers had done before, they have a lot of superstars pairing, but it didn't even materialized to get them into the finals and that includes PG as well. Not saying that it's the PG curse, but it seems that he is one overrated NBA player. And as much as we think that Joel Embid is very young, I do not think that he will be as healthy as when he won the MVP.
So waste of talent and there will be no process here, it will be better if Sixers will have to find a way to get a player that will really had a great chemistry with Joel. They have tried Harden, didn't work as well.
I think Maxey is already a good pair for Embiid. He can score when they need a fast-paced offensive strategy unlike when it's Joel, it's mostly post-up games and perimeter shots. So I think what they need are shooting guards that will probably help space the floor. Joel needs to have his one one-on-one against his opponent and the shooters will help scare their opponent when they leave them.
I don't think Joel is actually good at being paired so might as well just surround him with shooters with defensive capability and maybe that will enhance their chance to win a championship.
Surprisingly, the Jazz won the game against the Mavs. No Kyrie Irving for the Mavs due to a shoulder problem and Thompson cannot fill the hole.

The Sixers don't need a 3rd star in order to become one of the best in the East. What they need are reliable role players that can step up in offense and at the same time, good defenders. The best example right now is the Golden State Warriors. I'm not saying this because I'm a fan of Warriors, but looking at their current roster, they don't have an all-star player aside from Curry but look how they're playing right now. The team is surrounded with reliable role players, and at the same time, good defenders. Just for context, they're 4th in defensive rating currently.
The problem with Embiid is that, when they needed him the most, he's injured or not in perfect shape. For me, he's like the Kawhi 2.0. Embiid doesn't need shooting guards only for me, but the whole team needs defenders as well. Maxey like you said is a good fit already for Embiid. Adding PG13 could be good for them since they got him already, but what they need are role players.
As for the Jazz upsetting the Mavericks, this isn't a good sign for the Mavericks as they're 2 games below 500 already. I will not comment anymore on Klay because I know that he can't fill that hole.
