Outside of the US, very few places use MM/DD/YY. https://en.wikipedia.org/wiki/Date_format_by_country

Im in the US - and I exclusively use YYYY.MM.DD since its the only thing that sorts properly in a filesystem

At least Switzerland/Germany/Austria. I think most of Europe actually. The domain is .ch, so that will be the Swiss locale.

In my opinion there are two date formats that make sense: DMY (decreasing granularity) or YMD (increasing granularity). I tend to favor the latter because of ISO. MDY definitely doesn't make any sense at all.