True you could use a FAT or FAT32 drive to do that, but for beginners I just thought a single step write image to usb would be simpler.
I don't think you can use a partition on the Icaros desktop lite pendrive image to do that because it takes over the whole
drive according to the Icaros website. You could make an Icaros pendrive yourself to do that, but that would mean you already had
Icaros working, beginners can't do that. Anyway I was just thinking out loud, the distributions are very good as they are, it's just that
there is quite a lot that might go wrong at the beginning of trying to use them.