Your fanboy is showing here. You do realize that Kawhi's ceiling is the best player in the league? How can Simmons have a ceiling higher than that? Plus things change so fast in the NBA that you can't say the team is built for Ben and Embiid for the next 7 years. Players get hurt or move to new teams, new players come into the league and become stars and make other players expendable.
Every fan of every team in the NBA right now is saying we want what the Patriots have, or what the Spurs had, or what LeBron has done going to the last 8 finals. All those teams had all time greats, not just hall of famers, but 2 guys that are in the conversation as the best ever in their sport (LeBron, and Brady) and another guy that is probably the best power forward ever and probably a top 10 all time player. Plus there is the luck factor, almost never getting hurt, hall of fame coach (not always for LeBron), plus just being that good for that long. This isn't a knock on Ben or Embiid or any of the guys in the NBA right now, but odds are they are going to be more like Wade, and Barkely and less like LeBron and Duncan.