There's a difference. The AFK player doesn't get in the way, my friend and I are typically happy to have the strike to ourselves, we don't need extra help. The runner will run past optional objective and complete (or at least start) mandatory ones before we get there. So either we keep up with the runner and skip content we would otherwise be happy to interact with or we let the runner go off and complete another set of content that we want to play too. It's all about pacing, AFK players don't alter how I interact with the game, runners do. Not to mention their are actually runners who will grab a further checkpoint and then die [i]forcing[/i] us to skip ahead to his location.