Wouldn't that just delete the folder instead of emptying it?
You are in .; The current directory listing include ..; Recursively deleting everything deletes everything on the drive.
Actually, I think the one time I saw someone do this, wildcards were involved. And I was going to explain, but the comment system is making my asterisks into bold markers.
rm -rf ./*
rm -rf *.*
To stay on topic, because of this thread, I just added alias rm="rm -I" to .bashrc, and I have never yet needed -f.