The problem is that 900 people is a lot of people. Imagine all managers scheduling meetings with their reports to tell them, then the managers themselves are probably being let go, in the meantime it would create A LOT of stress not knowing whether you will be called in for a meeting or not, just sitting there seeing people being let go around you 1 by 1. The whole process would take a week just to have a proper meeting and give everyone decent time to process and ask questions.
In a way, I think this is better - it's quicker, everyone knows where they stand, there is no uncertainty about it.
However, I do agree that
1) the communication from the CEO could be better
2) people should be given an opportunity to then still ask questions, either for HR or their managers(if still employed).