I can’t imagine it being very useful in any of those cases as it would prevent you from concentrating fire. And you usually want to continue painting a target for missiles to be effective.
Anti-fighter weapons will already switch targets once the fighter is destroyed, dwindling the swarm of fighters down to nothing. There doesn’t seem to be a point to anti-swarm weapon that keeps the swarm alive by distributing fire evenly throughout the swarm.
But this order would be perfect for Shock ECM missiles and Shock ECM beams. Or maybe that should just be default behavior of the ECM modules.
Also, some players may find this order useful if their ship is equipped with disruptor bombs or radiation weapons.