Oswald - Not the hole in the tube beyond the pinch.
Where the tube merges with the side of the collar, on the inner side of that spot is a hole that the oil feeds from the tube through against/around the rocker shafts that fit inside that collar. Below is a screenshot from a 1955 Chevy Shop Manual that shows the oil flow (solid black including down inside of rocker shafts) from pump below and out the discharge end of the now crimped off rocker shafts collar feed. See the red arrow for where the hole I'm describing is.
The idea with pinching off the out feed tube came along in later years to improve a lack of oiling to the rockers, so yes, forcing the oil to the shafts and rockers.
