That's not true of most YC acceptees. It's more true of these "meet the batch" threads but that's a sample bias.

I suppose it's mostly an artifact of YC's growing so more internationally in recent years. There are others (e.g. https://news.ycombinator.com/item?id=28257352 and https://news.ycombinator.com/item?id=28087309) but these are a small minority.