Incorrect, there has historically been a "Permanent Floating WorldCon Committee" [1] that has provided a lot of continuity. Sometime they have fill higher ranking slots when the locals don't have enough experience.

[1] https://fancyclopedia.org/Permanent_Floating_Worldcon_Commit...

While the organisers have changed, up until this year the same person has written the un-audited software and run the voting process previously - which was how he was able to discard huge numbers of votes covertly last year, for example.