Heh you can perfectly disagree, but I can still say I find sniping selfish. Like all posts in a forum, it's an opinion, not a law. It's simply a matter of respect for your enemies. If you snipe people down, they don't have any fun. If you die in a duel or a large battle, you have had the fun of the fight.
And as I said, there are differences in turtling. Firing from a castle wall is perfectly acceptable, it is really necessary for your team to hold the wall. But I find it very selfish to sneak around the enemy army and fire in their backs from a place where they can barely see you. First, you are of no use to your team, because by the time you sneaked around them you could have done much more useful stuff. You will get 1-3 easy kills, before they know where you are, but you could have used your time for helping out your teammates. On top of that, snipers do not care about other people having fun, they only care about themselves.
I just find sniping selfish because I care about other players having fun.