They're missing a untrusted main character.

[FNGRpony 658]

See the problem with having a group of friends is if one of the main six knows the solution to a problem, 

it's gonna be a straight forward out come.

 

Yes i'm aware of swarm of the century where this very thing came up.  I kinda liked the solution was right in front of them.

 

I'm hoping discord gets an episode where he keeps trying to suggest something and no one wants to listen.
Discord
"wow If all i had to do make things worse is help out I would turned good a long time ago."

[Scootalove 10,692]

I could say that is what they are missing but, we have to wait until we do see Discord once again. So, there are many theories that can come.