The SM fractions will be the only one who not gonna finish the campaign !!!
Do you wont me to add something or this is completely enough for you ???

Orks is made for fighting an win.

Since Eldar and Orks are so much smaller in population than CSM/LSM, they tend to compensate by teamplay, although of course not always. But even then, they're simple not online as much as CSM/LSM are.

CSM, on the other hand, are in que a lot, with LSM mostly, but unlike 90% of LSM, the majority of Chaos tries to go for teamwork. I do get into matches now and then where there are newbies who don't seem to know what to do (quite possibly LSM runaways), but most of the time people from guilds (including me) try to take charge and lead a squad if not the whole team. Yes, it requires a lot of yelling, yes, you gotta be good with your fast typing, but in the end it works. And when all fails and you get defeated by those damnable 30 seconds - the Dark Gods will be pleased with any sacrifice, be it the enemy or their own servants.