The limitation is made to avoid problems with the file system on the SD card. FAT32 for example cannot handle files larger than 4GB.
NTFS can handle larger files (up to 16TB) but is not usable for the LINUX cores in the camera. LINUX file system (like ext2 or so) can also handle larger files but in this case Windows user cannot format SD card with it. So, they use the FAT file system as "least common denominator".
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