Keystone roof vents

Was on the roof today cleaning and inspecting when I noticed this roof vent cracked. Luckily the broken piece screws off without having to remove the whole unit.
Found new parts at the local dealer and I had to ask someone if they knew what these vents were for. One fairly knowledgeable tech says they were something only put on Keystone fifth wheels to 'equalize' pressure from the front cap through to the roof area.
He admitted that he didn't have a clear understanding of the exact nature of these vents but it was something to that effect.
Anyone else have any input?