Tim Bray: Red Herring: Statelessness · Statelessness isn’t an architectural fundamental, it’s a useful engineering technique for making distributed systems scaleable. Lots of Web-style applications keep all sorts of client state on the server and they work just fine. Those ones probably won’t scale up to serve all of humanity across the Internet, or even a hundred thousand busy online shoppers, but there are lots of useful apps that don’t need that kind of scale
It is worth looking at protocols that predated HTTP, like FTP. I agree that explicit sessions (via techniques like cookies or URI rewriting) are a part of the Internet as practiced today. However, it is worth pointing out that the trend is away from implicit state and multi-layered protocols.
I also find it facinating that people square off on REST vs Web Services, when SMTP and BitTorrent are the real winners.