I've been able to do the same since 1992, before "cloud computing" was ever in anyones mind. Drafts stored on the server, and accessibility (back then) provided by any terminal program. The only thing that changed is that the terminal morphed into the browser.

I suppose for many, GMail was amazing to them because their previous e-mail experience was with POP based setups, that encourage not leaving mail on the server. I made a push to move to IMAP after I used it on USA.Net in 1998. I had web mail, and a perfect copy of the state shown on the web site in Eudora. Once I moved off USA.net I set up my own IMAP server, granting me the ability to start an e-mail from any device, and finish it on any other. Including places like an airplane where connectivity isn't commonplace, since my IMAP client is syncing locally.

I'm still waiting for something cloud based to actually amaze me. So far, most of the things going on in the cloud are just rehashes of whats been possible for decades. The only difference now is the end user is losing more and more control.