Horford has 3 years reamining in his contract until he is 36, at almost 30M a year. He will soon become washed and thus, one of the worst contracts in the league. You can argue it's one of the worst now as he is looking terrible already. Even if Conley plays only decent bb, he comes off the books in one year and therefore, doesn't cripple our ability to resign Rudy & Donovan without going deep into luxury tax territory. And it's not like you can get great 1st rounders from Philly for acquiring that albatross: they are full of meaningless 2nd rounders. Basketball wise, it makes no sense either: he doesn't fit our system, positional need or timeline. It just doesn't make sense. These are the type of moves you make when you are rebuilding: you absorb a bad contract in order to get decent picks. We are buyers right now, plus Philly assets suck.
You can do better with the trade machine my friend