How the H*** can this be common sense ?
The Achievement says "Kill all bosses blabla" , so since the "new" guy who joins raid havnt killed a single one, noone would think of this as common sense .. Dont think you know wtf common sense is .. So I give you an example .. Common sense is like when you:
1. Mount on flying mount > Go 1000000000 yards up into the air > Release and when you land ...... dead .. (Common sense)
2. Trying to swim to GM island and dies of fatique (Common sense)
3. Light a firecracker in your mouth instead of a cig and get burn marks or worse (Stupidity, like your comment)