When you view someone's profile from the leaderboards you can only see their currently equipped gear and skills, and it's usually not the same setup they used when they got their rank. The character model you see when holding your mouse over their spot in the leaderboard gives you the look of what gear they used, but there's no way to show the stats or skills. The items can even be transmogged to look like something else.
What's the point of keeping it secret when most of the builds end up as a youtube video anyways?