On newer EFI engines, I believe, at least some, manufactures went to a closed system, where they removed the vent on the opposite valve cover and plug it off.
I have heard different theories, as to why. If you evacuate the air from the crankcase there is less energy wasted spinning air. It reduces the amount of air pulled into the EFI system that is not measured.
I do question a closed system at WOT. It takes little pressure to push
oil under a gasket.