I thought Horford would be a great fit. He can stretch the floor, play defense, and he is a low-usage, low-maintenance player.
The problem is that Ben Simmons would be unstoppable with four shooters around him and Embiid would be better with a pick-and-roll point guard that can shoot outside.
A team of Simmons, Covington, Horford, Harris, and Jrue Holliday would be a much better team than one with Embiid. A team of Embiid, Covington, Jrue Holliday, Harris, and Horford would be a much better team than one with Simmons.
Talent doens't always win out.