I'm not a moaner, I'm just being realistic.
Certain acts/events draw certain crowds and stages should be allocated suitably.
Glastonbury is an example of this, they put Jeremy Corbyn on the Pyramid stage as he drew over 200,000 people to watch him. A less popular act would have been on the other stage.
25,000 in a full stadium looks a lot better than 35,000 in a half empty stadium, it's all about image to the punter watching at home.