However Orks are renowed for loving to get close and personal, and more important, they need strong leaders to keep them going togheter, even in the face of a clear common enemy.
There was actually a war where tyranids droped in an ork planet and were repeatedly crushed and forced into guerilla warfare, and even then things looked grim for the nids.
Until the tyranids realized the ork large numbers were just kept in check by a specific warboss. Using taunting hit-and-run tactics they lured said warboss in the open and killed him. The orks hordes proceeded to break in in-fighting and the nids picked them off one by one.
No special reason why the zergs couldn't do it, in particular because they're infamous for infiltration and dirty tricks.
Originally Posted by GolemsVoice
That's just deuterio. He seems to hate W40k with a burning passion and injects himself in every debate involving 40k. It's not the first time it has happened
No, I just happen to actually read the sources.
There's at least hundreds of chaos warbands
out there, and each chaos warband is roughly the equal of a loyalist chapter
. Since each chapter is around 1000 strong, then simple math confirms that yes, there's hundreds of thousands of chaos marines out there.