Mk3 Oil Seperator Moulding

All parts exploded in mk3 parts book or on AN site:

https://andover-norton.co.uk/en/shop-drawing/141/oil-tank-and-fittings-oils-lines-cartridge-filter

Bottom part of pipe 32 goes to 2nd outlet on top of oil tank. Pipe 37 and grommet 38 go into the back of the big black air box. T piece 40 is to the connecting pipe between the carbs.

As grommet 38 is in the air box, this dictates its position.

I have done away with the air box and run K&N filters - pipe 37 now goes into a small bottle which is tied to the left hand frame rail near to the battery.

I'm grateful for that description too, as that arrangement is listed in the parts book for my MK2A as well, but the parts illustration alone tells us almost nothing, and the hose from the top vent on my bike's oil tank just goes straight through the grommet into the airbox, with none of those bits and pieces. Presumably someone's ditched that set-up over the last 43 years or so. Whether or not I fancied re-fitting all those parts for the sake of originality, I have to reveal my ignorance and admit that I don't see the point of it! Would someone explain that to me? As I see it, any oil that's separated would go to the airbox, as it does now, and the air would go to the balance tube in the manifolds, presumably weakening the mixture somewhat; or maybe I've got that the wrong way round. Either way, it seems a very complicated way of tinkering with fumes from the oil tank only to send them all through the combustion chambers anyway. What am I missing?