I doubt that Kellogg or any other schools extended deadlines (waived test score requirement) because they wanted to generate extra revenue. There could be other motivations.
Interestingly, there used to be a message in the top right corner in my Kellogg's application portal that said something like "thank you for applying in rolling R3, we will be in touch about your interviews in the next few weeks. With questions email interview coordinator at ...." Now this message is gone.