[Krsqk]

In my experience, one-sided battles rarely result in great numbers of damaged ships. Many/most players use compact formations which allow concentrated fire on a few targets, rather than spread out fire. If one player concentrates fire and the other doesn't, the spread out player will die. He will constantly lose firepower, while the concentrated player stays consistent throughout the battle. The exception is if the spread out player has vast numerical superiority (which results in concentrated fire on a different scale).

Two reasons concentrated fire is so common on PBW are 1) it works , and 2) strategic combat tends to use concentrated fire.