Actually, it's not. Taken by itself that snippet implies that Blender auto-saves changes made to open files. In fact, quit.blend is just the contents of the *last* file touched -- meaning, for example, if you are working on one file, then open another, you lose everything, and quit.blend will have stored the unmodified last-opened-file. Plus you still get no warning/confirmation-interrupt that the file-open-operation is also destructive. The proper way to do auto-saving is the way Inkscape does it (per-file). And even if it did proper autosaves, it still doesn't make up for lacking confirmation-on-close/quit-with-unsaved changes, which is the root problem. Autosaves are supposed to be for crash recovery.