Hi Fyron
I think your post basically says it all.
You have probably considered this, but the way I look at intel is that it is just another way of waging war.
I agree with you that it is not 100% in tune with the real world in the sense that it is completely realistic.
But in the real world, intel can cause a rigime change and thereby effectively remove one of the parties from the game.
IIRC, the Germans harboured Lenin. When WWII started (or maybe before), they helped to smuggle him back into Russia.
He was a major participant in the 1917 revolution and with the rigime change, a new treaty was forged with Germany in which Russia's status changed from enemy to neutral/friend, thereby allowing Germany to transfer the majority of its forces to the western front.
In a sense, Lenin could be said to be a effective spy.
So, one could argue, that Germany won the war with Russia by removing Russia from the playing field by undermining the Czarist government.
I would think it was cheaper for Germany to remove Russia through insurrection than to continue to expend material and human resources in battles with Russia throughout 1917 and 1918.