Recently, There seems to be so many multiple accounts among various rating ranges.
In top 10, there is -0.5, who became Legendary Grandmaster in 2 months. He should be a great genius, right? There is better hypothesis: He is someone's smurfing account.
Everybody knows that jiry_2 = Syloviaely. He performed quite a long ago, but it's the fact that he has multiple accounts, both having 2900+ ratings.
In Div2 contests, many black-colored people are at top of the scoreboards. Why there are always a lot of talented newcomers? You will know the reason.
Why don't Codeforces ban those multiple accounts? They ruins contest scoreboard and rating system. For example, -0.5 "absorbed" other participants rating for about 5-6 contests to be Legendary Grandmaster. On those contest's scoreboard, there were always him on top pages.
One account for one person. That was the rule. Smurfing accounts should be banned.