I always help kill spawned mobs after mine go down because its an MMO and I think I am being nice to other members of the community.

imo you don't like help from other ppl either wait til there is no one around so you can pull it off the side and do your thing, or switch to a single player game.

In an mmo mobs should not be restricted to a single player, it was nonsensical in ffxi and it would be here too.