I don't think that limitation comes from a matter of difficulty, even for the first time going in with the appropriate level; it's simply that -qi only allows for 7 portraits to be displayed (you+backpack+material bag+4 other mates), and thus only 5 chars to be healed/buffed/cared for/saved in time without having to permanently hit alt key looking for the right health bar. Just to avoid stupid deaths, actually. "Damn, sry, u weren't even on -qi, thought we were only 5" (happened dozens of times in fights against foothills worldbosses).