I am sure it has to do with the scavenging of the bearings rather than the oil feed.
Had there been an issue with the oil supply, the main/big end bearings would have failed first.
The scavenge lines (for all cavities except the crankcase which doesn't need one) run from the 'air' side of the oil tank. They only exists so that the cavity can 'breathe' as the scavenge pump pulls the oil out. If for some reason oil starts coming through from the oil tank the bearings can get flooded. The last thing you want is a 125k rpm shaft running in oil.