The rewards for Rank 1 are easily achievable in a fraction of the time using Explore mode. If the #1 player really wanted those stones, instead of the (lower-case) glory and fame for ranking at the top, they'd just do Explore.
The purpose of the leaderboard is to make those who are unable to invest the time, jealous enough to either put in more time, or ideally money, into the game. It's a carrot at the end of a stick, but the closer you get to the carrot (in terms of win efficiency) the more you realize how inconsequential the reward itself is.
tl;dr: Nobody is winning the leaderboard for the stones.