It's likely due to people being lazy and using their SB poker for EVERY RB. I keep a poke 2* in Team 2 and 3 6*s as a mini-nuker in Team 3 and it works OK, though the 3 6*s tend to take off over half the HP if the boss is under level 70. Might fine-tune that, depends on forum preference (if it's fine to have me do lots of damage to non-SBs, I'll default to Team 3, only using the lone 2* for SBs)