[ajross]

It's neither really. The reason is that the data filesystem used to be FAT, so that it could easily be read by host computers using the preexisting USB Storage standard. But FAT sucks (for reasons too numerous to list here), so they went with ext4. But that can't be mounted on anything but a linux box, so they had to pick a new file exchange mechanism. It could have been something like SMB over a USB CDC network device (phones have done that in the past) but they picked MTP instead.