"When I was a kid, when we shrunk a 200x200 image down to 100x100 we lost information forever, and we liked it that way. It was a simple time. A predictable time."
Once you export it is, of course, actually downscaled.
Same idea behind masks and modifiers and the like. Most modern creation tools try to give ample opportunity for non-destructive modification to simpler, immutable primitive layers.