Autocomplete and autocorrect are "guess what I intended" functions. The problem with shells is that the UX is crap: User actions are often executed immediately (review time between typing and executing is a fraction of a second), and most importantly there is no undo. This makes guessing a bit dangerous. However, the fault is with shells, not with guessing. If you never instanty execute anything without review then the issue nearly goes away (more like regular programming than a REPL).