I think his point was that, it only back up the crucial data. And he added a further point.
"Remember, if you could nandroid your entire device.... You'd need a massive amount of free space on your device.... Like half almost of your storage free. Then after your nandroid, You'd have no space left and in my case, a 14gb backup file."
"Not many people would have the space to backup up their entire review, therefore cwm/twrp gave never considered having that as an option."
I countered his point saying that, if you have a huge external sd card, you could do it that way. But anyways, at this point I believe him. Unless you can show me in a youtube video, or exactly what to do. Or prove otherwise. Well, that's it. I'm just here to learn, I'm still new to this stuff. I don't care who is right and who is wrong. It's what I can do, lol.
From what I can tell there is:
System rom storage
Internal storage
External storage
And I don't see /data/media folder in my Internal storage.