Embiid is a 26 year old 7-footer who can put us 25 pts and 12 rebs. I don't get why people are so down on him. In fact, I think Houston would likely just take Embiid and the others over taking Brown et al. from the Celtics.
In terms of a trade based on Embiid for Brown, I think the Celtics would do that. I don't love giving up Brown and Embiid has durability issues but 7-footers with his skill are a lot more rare and harder to get than good wings.
1. He's not suited to the modern big man game. His outside shot is highly inconsistent, he can only play and defend one position so he has zero versatility, and he lacks the footspeed to be able to defend the P&R (or anything outside about 5 feet)
2. He lazy and out of shape. He's lucky to give you half a game at max (or close to max) ability before he gets winded and drops off to 30% of himself for the rest of the game. He puts close to zero effort on defence, regularly standing around watching instead of actually defending and frequently walking at a snails pace up the court on defence.
3. He's got a disgusting personality, being both arrogant and egotistical. He constantly brags about how great he is or about how much better he is then his opponent, which is made all the worse by the fact that hes a poor leader who has never won anything and constantly gets his butt handed to him by teams that he's supposed to have a clear advantage over. He needs to learn to respect his opponent and actually WIN SOMETHING before he decides to walk around bragging about how great he is.
4. He is physically broken and cannot be depended on to be on the court when you need him. The man has played in only 39% of possible games over his first seasons in the NBA (158 / 410). That's almost two thirds of games missed over a 5 year period. He can't play full games because he lacks the fitness, he can't play back-to-backs, he has potential to be stuck on minutes restrictions at any given time. And while he may only play in a fraction of his games, he certainly gets paid for all 82 of them...
Embiid is a mess, and not somebody I want anywhere near this team.