Sure very easy fix... until you go from 199 to 200, and loose your rank because you are now at the bottom of your range instead of the top... Resulting in people having to stop playing at some point to keep their rank.
Also, the person that can get the highest paragon 100 rank will become number 1 by default in his paragon range, removing the leaderboard competition for the most active players, focussing even more on the pure paragon grind?
Giving everyone his own leaderboard (people hit paragon 2000 or so, with a board every 100 paragons, that's 21 per class, good for 126 leaderboards!) is not a solution...
Would also work great in party setups... Based on highest paragon? Or lowest? Average? Or a million "leaderboards" for every combination?
So while it might seem easy to do it this way, there are so many issues with it that there should be another better solution.