Yesterday when I was playing a strike playlist mission half way through it occurred to me that there were only 2 of us actually playing. We ended up completing it with much difficulty, and after a long, long time, turns out that guy just waited at the start and still got rewarded for it. I don't know if this was on purpose or not but knowing people could easily do that really annoys me. There needs to be some kind of way to prevent this, I did think a spawning system like Halo did where when one of you gets so far the others spawn next to you, however I don't think that's the best solution.