crankcase venting

Can anyone tell me why I need a PCV in the hose running from the timing
cover vent to the intake manifold?  If the oil filler cap is not vented then
the only flow would be the blowby gasses heading for the intake manifold.
Would that be enough to cause a problem?  Heck, I'm tempted to just try it
and see what happens.

I still have the typical "teaspoon after every run" problem with my 1275
even though I added the hose (with PCV) between the cover and the intake.

Thanks,
Glen Byrns