Ultimate Bravery

Why is Ultimate Bravery not a bannable/reportable offense? I went into two matches with the same group of 3 players who decied to queue up and do ultimate bravery, but not only were they doing that, they refused to run from any fights, and so they would run into 3v1 fights as an AP J4 or a Hybrid Darius, effectively throwing the game because they fed the enemy team, for lack of a better way to put it, on purpose.