My solution - don't ride on a trail.
All kidding aside, have no idea if this is an actual problem. Never heard it was, but the only symptom, short of a sucked in bottle (don't think that would happen) or blown motor, is less oil use. (Poo's new EPA compliance technique!) About the only way to test it - take two sleds that consistently use the same amount of oil in a day riding together. Put a fully vented cap on one, and the stock cap on another. See if the stock capped sled now uses less oil, day over day. Don't know.