Hollow boards require a vent to be able to equalize internal pressures from changes in temperatures. If you surface mount a plastic vent or make your own brass vent you do not need to install blocking and you can simply drill a hole. For a more professional look you can countersink the flange and have the vent sit flush or just proud of the surface.
This 1/8″ rabbit allows the vent to sit just a little proud of the board but requires internal blocking of some sort. Vent blocking does not to be overly structural as it doesn’t get the pulling forces that leash blocking gets and its main function is make sure the vent isn’t a weak spot. There are 3 main ways to install plastic screw vents: