And it's for this reason that it's always written 5/4, and never 4/5.
Yes, 4/5 technically exists because it's created in a sequencer. But what happens if you put it to musical notation for some reason or other (or if you're bound to)? There are no notes with a 5-count at all. There are whole notes, half notes, quarter notes, eighth notes and so on. Those are all multiples of 2 counts. And then you have the dotted half notes and so on, which are multiples of 3 counts. There is no single note in music which equals five anywhere.
So you can have anything ending with /2, /4, /8, /16, rarely /3, but NEVER /5.