theoretically yes. effectively anyway.
in practice, I don't think I've ever seen a sticky footer that didn't flake out somewhere. it's always broken weird screen sizes, or mobile, or one browser, or after a browser update. or it hides content because someone forgot to add padding. or it jumps around because they're using absolute position for some insane reason.
it can even be sticky at 2X or 3X the screen hieght so that it doesn't get in the way of the freshest/most important content near the top of the (very long) page.