DE 1vs1 starting ELO

Hi,

I noticed strange thing checking historical ELO's in DE. I see some people started their journey by being at 1000, while myself was 1200, 1238 after first win. While Hera and Viper started at 1600. Is this because they are pro players? Why then the difference between 1000 and 1200 for some people? Also noticed that lower end of top 100 players mostly started at 1400.