It's funny because I had to take a company mandated 2 day Agile training class, and I thought the exact same thing. I thought "Waterfall" was just some concocted fantasy workflow to contrast with. I actually asked our instructor if it was real and he said "Of course it was!"
Waterfall was named as a strawman. However it is very similar to what a lot of projects do. No project does waterfall as described because there are always things that can't work that way. (some projects get closer to waterfall than others)
Now I don't know what to think!