Isn't it still a default somewhere? I recently formatted a pendrive on Windows and somehow mindlessly selected FAT (and ofc had troubles down the road). I probably picked a default somewhere. And to respond your question:

>Why on earth would you do that? People have been using exFAT for many years now.

Most people have no idea what FAT is. If presented a choicee between FAT, exFAT, NTFS and ext4 I'm certain they don't care, don't understand the implication, and would just click a random option. Which is OK, not everyone should be a IT expert, it's MS job to make the experience smooth.

edit: and a technical reason: i think FAT32 is the only guaranteed fs supported by UEFI

>If presented a choicee between FAT, exFAT, NTFS and ext4 I'm certain they don't care, don't understand the implication, and would just click a random option

I think it would be quite rare for someone who has no idea to even be presented with such a choice in the first place.