Operating systems have always used their own filesystems, and it persists to this day.
The only obvious exceptions that come to mind are iso9660 as a standard for CDs, and people generally go out of their way to use FAT/FAT32/whatever on USB keys and SD cards for compatibility with cameras or whatever device they're plugging the card into. But the latter is a choice users actively make to ensure the FS is compatible with the device, rather than a default.
Operating systems have always used their own filesystems, and it persists to this day.
The only obvious exceptions that come to mind are iso9660 as a standard for CDs, and people generally go out of their way to use FAT/FAT32/whatever on USB keys and SD cards for compatibility with cameras or whatever device they're plugging the card into. But the latter is a choice users actively make to ensure the FS is compatible with the device, rather than a default.