And why is this? 90% of any given group in the game is a PUG. People run PUGs for missions, for quests, for vanq runs, for dungeons, for high-end areas...I'd say basing my findings on the form of grouping that is by far the most dominant one in the game to be fairly logical.
Pugs are also the same people that run warriors with firestorm and think nukers>>>>>>everything. If you're going to base these things off people playing the game base it off the enlightened people who actually know what they're doing and are competent. Never seen people pug vanqs or dungeons in my years of playing this game unless you're counting people buying runs. I also don't see many people pugging at all. Most outposts for missions and such are near dead as most of the people playing the game have had it for a while and have beat it. Only elite areas I've seen people look for pugs in is UWSC and DoA in the ursan days.

