A rough draft is something you dump on
Everything to show everyone that you're a
bona fide writer.
No, seriously, a rough draft is an important step in the writing process, even though you're writing on a computer and can continuously edit a piece.
After you're done writing a rough draft, that is, after your piece has a beginning, a middle, and an end, and you've said the basic things that you want to say, then put the piece aside for a while. Later, come back to it with the ability to read it and have it make a fresh impression on your mind. Even better, have someone else read it if possible. Either way, you should get a clearer idea of what it is you've actually managed to say with your writing than if you are continuously rereading it an changing a word here and there.
If you like what you've written after giving it a second reading, then you're lucky. Touch up some sentences here and there and call it done. More likely you've seen some paragraphs that need to be removed, some additions you should make, and some rearrangements that might make the work clearer or more organized. It's difficult work, revising things, but it definitely makes your writing better in the end.