Levels and XP points

What are levels and XP points for? Is it just only for decoration?

I have a proposal about this scoring, maybe you could reward users with high high level (and XP points) of some kind prize e.g. a price reduction to access to the Cybrary (discount codes).
It would be motivating in some way.
After all, people with a high scoring have passed most of the materials (courses) and sometimes there are not many new for them, and are not interested in keeping the account for which they must pay the full price.