My one and only devils advocate to your suggestion is that 5 people can kill things 5 times faster. So while your solo guy takes 10 minutes for a collection quests, 5 people won't take 50 minutes because there would be less downtime and mobs die faster. Of course, then there's the issue of total available mobs without waiting on respawns to counter that but whatever.

Obviously as a multi-boxer I like the idea. Good luck though, I'll /sign whatever suggestion you make along those lines.