why is solo/duo off at 3am AEST?

Last season we finally had ranked on after 3am so I question why is solo/duo off?

Is it to try and force solo players to play flex? I feel it is unfair for the players that play at that time to suffer so you can push a que that is obviously failing.

You already enforce auto-fill once every 3 games and que times are hitting 2-10 mins leading up to 3am so why the need to shut off the que?