I don't think lurking has much to do with shyness. More likely it's the knowledge that when you do post, one of three things will happen: (a) you'll be ignored, ( you'll be told your topic has already been discussed to death, or © your thread will promptly veer off into endless discussions of military arcana that have little to do with the enjoyment of Combat Mission.
Not that there's anything wrong with that. Grogs are people too, and this forum is as good a place as any for them to plumb their passions. But many of the threads here can be kind of daunting to someone who just played "A Chance Encounter" and wants to talk about it.
Or it may just be that lurkers represent those perverse CM owners who prefer to actually play the game, rather than complain about historical inaccuracies or wade through epic treatises on, say, HVAP slope effects. These are folks who, under different circumstances, might ask foolish questions, or offer foolish anecdotes, or compare notes on favorite foolish scenarios. They should probably get their own forum.
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"War does not determine who is right - only who is left."
-Bertrand Russell