For teams spread across time zones
When there is no hour everybody shares, anything synchronous excludes the same people every time.
The specific problem
A team split across enough longitude has no shared working hour at all. Rotating the pain sounds fair, and in practice means everybody is tired some of the time instead of one person all of the time.
What changes
The round belongs to the team's own clock, not the server's calendar, and it stays open for the day. Scores reveal together, so playing early is not an advantage and playing late is not arriving after the ending.