"Muh last gen" is probably the first excuse they'll offer. I really have no idea how complicated adding custom games/private lobbies is but considering pretty much every shooter ever created has them it's weird that it doesn't exist in destiny. Your guess is as good as mine. They also had split screen ten years ago, it's weird that a ~~~party game super social~~~ hyped up game doesn't allow you to play with friends on your couch.