2 advantages.

First is that u are not feeding engine with oil to burn. An engine in good condition won't breath heavily though, mine barely at all, although ive seen others that piss out black smoke from breather. Oil in the combustion chamber is a major det causer.

Secondly, you will reduce crank case pressure, although not as much as with a proper swirl pot. This can help if u have problems with oil cap/disptick blowing off. You should see a reduction in oil consumption.