NSMBW sold more than 10m copies in three months. Even if NSMBU reached the cap of 5.5m for its first 4.5 months, it would have fallen short of NSMBW's sales.
10,000,000 is a much bigger number than 5,500,000. Get it?
Yeah, I get it. You don't get my point. Even if it could have, it still wouldn't have, because even when limited, it never reached that limit. You get it?
i.e. it never reached 5.5m, so the limit was rendered powerless as a constraint, in the context of your logic.