Earning gems instead of coins

Why do I only get 100 gems instead if coins after either the leaderboards or club perk levels each week? I prefer coins.

Gems are the reward of you are top 5 in Platinum league and if I remember it’s the same for gold league. I don’t know what the payouts are for the other leagues Anything below that is a coin payout. I like the gems (save them for emergency) when I run short on boosters or purchasing a chest if I am wanting coins also