Fun fact - in Polish we have separate forms for 1 (singular), 2-4 (plural but nit many) and everything else. Zero is in “everything else” 0 książek 0.5 książki 1 książka 2,3,4 książki 2.5 książki 5 and above książek 5.5 (any other fraction) książki >100 and a fraction - depends Singular is for one. The first plural is for things kind of treated as individual objects. The second plural is for things that are treated a…
I always explained it to myself that, when you use a fraction, you're focusing on that one incomplete object, also calling more attention to the individuality of objects in the set. So in case of say, "100.5 książki", I like to imagine shoving ~95 books into the box very quickly, then slowing down for the last 6 books, counting them off one by one, to know exactly when to stop and saw the 106th book in half.
IDK what the official justification is.