All you have to do is stumble over to one and start hitting things: your actions automatically add to the overall task for everyone. So there#DY#s no need to roll your eyes in disbelief when a note saying you need to kill 100 militiamen pops onto your screen - even with just half a dozen players, that#DY#ll take no more than a few minutes. Once done, there#DY#ll be a second stage, which generally involves slaying just a few super-tough baddies. There#DY#s a bit more emphasis here on working together, at least compared to the wild free-for-all of the first stage, but all that really means is hitting the same thing as someone else rather than tackling an enemy on your own.
It#DY#s subtly introducing the rudiments of team-play to those who usually hate and fear it, but again, absolutely no communication is necessary. Which makes a lot of sense, really: WAR is a war, and wars generally don#DY#t involve soldiers introducing themselves to one another and politely inviting them into their party just so they can go fight the enemy together. The final stage is always something substantial: a boss foe, whether it#DY#s a hard-as-nails hero character, or some epic monster like a dragon or demon. Cue a massive pile-on and, presuming the fight goes well, a sense of heroism generally reserved for the climax of a three-hour dungeon run.
Only, this whole process has taken less than 20 minutes, and didn#DY#t require any of the tedious organisation and hanging around waiting for people to fly over that your everyday raid does. It#DY#s one of the reasons people play MMOs: to fight something really, really big. At last, it#DY#s something you can just go and do, rather than put the amount of effort required to organise a charity fun-run into it beforehand.