If you just want a scattering of reprisals here and there, no leader needed.
If you want to wipe out the enemy, a leader is needed to define the mission, recruit members, inspire action, provide strategy, adapt to changing conditions, communicate with each other, etc.
Just like on the battlefield.
I'm not advocating anything. IMO, if you or anyone wants to see this happen, then you have to take out the enemy entirely and quickly. That requires leadership.
The 'leadership' will be the military command, who will deal heavy punishment on Islamic states. On the ground in the USA, individuals on their own initiative will initiate a cleansing campaign here at home, and the authorities will be loath at best to stop them.