Why is dribbble's work space so limited? Only 800*600?

Why is dribbble's work space so limited? Only 800*600? It's hard to tell what our design content is. Is it difficult to express the integrity of the design? Why is that? I just came to dribbble soon, I am very puzzled, what do you think?

This is my college packaging design class homework.

RED BEAN PACKING DESIGN