Can you source that 10% claim with a reliable source that isn’t outdated?
Besides even if the 10% was true it means that there’s hundreds of thousand of players in diamond. Then when you consider what kind of players most of the low tier players are like anything between casuals who have less than 100hrs into the game after 4 years because they play only one or twice a month to some random dude playing at 12fps being hardware stuck despite having a thousand hours. Since there’s an abundance of these players in the lower tiers even reaching the top 10% isn’t an achievement