Most people can do all of the moves, but don't utilize them all in a match, as there are often moves that are less useful. Feeling like you have to use every move in the book to be playing your character properly is a really common misconception, and one we see posted pretty often.
The main problem is that it puts you in a mindset where you're thinking of moves you have to do, as opposed to using the move that's appropriate for a given situation. If the situation calls for you to use B,B over and over again because your opponent won't stop attacking, then using B,B is the correct thing to do. Players will often ignore this though, and continue to try sticking in different moves, because they think playing at a high level is purely about how much "stuff" you can do.
An important point of growth as a player is realizing that the game isn't about just doing "stuff." Rather it's about properly utilizing all this "stuff" in the appropriate situation.