Occasionally someone else's fight will fall into your lap. For example I once undocked from a base to find a lane hacker gunship and a liberty gunboat in a fight. It looked to be extremely balanced between the two, but I choose to assist the hacker. I hand a full load of slaves at the time, so if the LSF won I was going to have to deal with him anyway.
Of course stuff like that isnt what the complaint is about. The complaint (from my understanding of the post) is the fools who go looking for a fight to jump into. This is a very very annoying habit that some players have, and it ruins things for the rest of us. Not all rp battles get planed on the forum, and to have one side that didn't need the boost getting one just sucks the fun out of everything.