Many people play with rules most common are max 10% of points for artillery in a meeting & not hordes of size zero units. I think it has come about because some people bought very silly forces so stops them wasting your time fighting them, a case of a few people ruining it as per life. Many players once they know you are sensible then do not worry about to much or use house rules to create specific situations.
Here is a link to realistic arty use the last post
http://forum.shrapnelgames.com/showthread.php?t=44344
As you can see force size not map size is what matters most & 10% tends to allow more than the correct meeting allotment