I really like the team nature of it. I have only been playing for about a year, so there are a lot of tiers where I haven’t bothered parking a good seasonal at (Gold for example, the worst!). I like being able to get help with those tiers, and maybe I help someone else out in Harbinger because I parked some good dragons there. Also, in Red one Kinnara may not be enough to get through (especially without auto attack), but invite a friend and you can use two.
PS: I joined like a week and a half before auto attack became a thing, how did people use sorcerers before that?