The biggest limitation for most people when it comes to building in LEGO is not having the right parts, or not enough of the right parts. Particularly when it comes to the giant thousands of brick designs that people sometimes come up with.
Fortunately LEGO has a solution for that. It's called LEGO Digital Designer and it allows you to model your creation on your computer. It will even give you a list of required bricks and build instructions.
All of which is a long way of pointing out that while the designer of this amazing Avengers Hellicarrier LEGO model Yo-Sub Joo has not physically built the model, it is nevertheless a legitimate LEGO model, and a huge one at that (22,694 bricks!)