My cousin works for Cover, here is what he told me:

Gura just gave Cover the biggest ammunition they could have asked for.
Cover management was getting fed up of all those talents who want to leave, and they decided to change how things are done after Aqua graduation.

There is a reason why JP talents ignored on twitter Gura's graduation, JP management told them to do so.
The only reason why EN management didn't do the same, is fear that some of the more strong willed talents would open their mouth (Kiara and Calliope), so they left it open.

HoloJP also denied any support to Gura's graduation, that's why the 3d live was a huge flop.

All of this was done to show the lesser talents that they are nothing without the company, DON'T THEY DARE LEAVE OR DISOBEY THE COMPANY!
Even with 4.6 million subs, she couldn't do much without the company fully backing her.

They all know that if Gura made a 1 hour long graduation stream on a weekend, she would break records and achieve 1 million CCV. That's why it was so short, that's why it was on a work day, that's why it began when japan was still sleeping, that's why JP didn't repost anything about it.
They have the data from previous graduations, they know the conditions for peak CCV to happen.

Cover won, just watch as there won't be any graduation so soon.