FF crop does nothing other than throw away pixels. It doesn't add any 'reach'.
You say "throw away pixels", I say "allows me to buy cheaper lenses that get to supertele, without extenders that add cost and rob light, without photoshop". I love full frame and mostly shoot wide, but if I was a birder who liked to travel, a crop R5 with the RF 100 - 500mm would give me a 2-piece setup that gets to 800mm effective and fits in a backpack, with usable files straight off the camera. That's never been done before.