I think they are mostly for little kids who have a few cards they want to keep with them. I don't think they hold an entire deck, not sure why you would put a deck in one since you would have to take each card out indivisually. they aren't really good for displaying cards either for collectors since they are flimsy, small, you can only have one card per page. I prefer 9 page binders to be honest.
I definitely wouldn't put an ex or ultra rare in one since they are flimsy. I'm not sure if you can put a toploader into it. But even then they only hold so many cards. I would probably need to own 30 just to hold my ex collection.