It doesn't matter how good applications are at remembering state and how well copy and paste works. There is no way to make context switching as seamless as it is with multitasking. If I open two applications side by side, to switch between them, I <i>move my eyes</i>. I can be reading something online as I type an email without even looking at the email window. While I'm typing this post, I'm watching the progress on a download. There is no way to accomplish this without true multitasking. Faking it with quick application changes doesn't work.