Eligible anime for the awards must have been released between Summer 2018 (July 2018) until Spring 2019 (June 2019).
The winners were selected via fan vote, but it should also be noted that the Machi Asobi event is organised by Hikaru Kondo, the president of ufotable, which animated Demon Slayer: Kimetsu no Yaiba.
However, since the anime won via fan voting, it would be safe to say that the organisers had no hand in the anime dominating the awards.
You can also read more about anime here on SGCafe.