Good point about it not being an optimization – calling it "tail call elision" would be more correct. And it's true, as @pflanze's comment correctly points out

Good point about it not being an optimization – calling it "tail call elision" would be more correct. And it's true, as @pflanze's comment correctly points out and I think you're getting at, that loops aren't sufficient – but gotos are. Of course, then you're programming with gotos, which may not be awesome. But point taken.