there could be hundreds of reasons for this. I doubt it's any one particular factor. Without real data and survey data I imagine it's hard to pinpoint. About any reason we throw up could be plausible or false at the same time. We can certainly take guesses, but I imagine Sony has the lions share of defectors(from Xbox) so if they happen to not like the product they either went back to Xbox or stopped purchasing content.Didn't someone earlier state that there's proportionally more "core" gamers on Xbox One compared to PS4? That seems like the only logical conclusion to me. Unless Ubi sold some Xbox exclusives?
It could also be the age factor, Xbox one owners may overall be an older population with more disposable income (let's assume media features was a big deal for purchase).