Anecdotally and from personal experience (particularly from my younger days of doing shit like taking 3 day wilderness treks with groups and then sleeping in big cabins or tents) I would suspect a lot of it has to do with the propensity of one gender, in particular, to snore louder and more than the other.
for Christmas. It stopped my snoring immediately and permanently! She says it's the best $100 she ever spent. The only downside was that it gave me a stiff neck for about a week until I got used to it. Now that my neck's broken-in, it feels comfy. I might get one of the mini pillows they make for travelling since hotel pillows are usually too soft.