I just don't see enough people who would benefit from that feature compared to the amount of time it would take me to add and, more importantly, support it in Rufus. On the other hand, Rufus also supports Linux, DOS, UEFI and other boot modes, so adding exFAT just for Windows images, and just to satisfy the very few people who will want to use their bootable drive between a Mac and a PC (and MUST have a >4GB file to justify not being able to use FAT32) seems like a waste of development time, to be brutally honest. Also, I'd be very surprised if that exFAT drive boots in UEFI mode. So that's probably why it might be easier to make it work with exFAT.
This software currently only support Windows bootable disk, can work with both BOOTMGR and NTLDR boot mode
