A swarm, or things are in tight formation, or just ships near each other, you know like every game.
Ah, if you use such upgrade cards on every ship in, you know, like every game, then fair enough.
99.9% of my games are about 5-8 ships duking it out. On the 0.1% of games where such upgrade cards are used, only 1-2 ships use it so it's not very confusing.