This creates quite a clear communication protocol: The person asking for a date: If you ask for a date, (or have a date cancelled), do not ask again, it’s up to them to suggest an alternative.
The person being asked for a date: If you’re unable to to make it on that day, or you have the date arranged by have to cancel – then if you’re interested in dating that person it’s up to you to immediately suggest an alternative date.
This isn’t bleak reflection of the state today’s social dynamics, it’s just how it works.
It might not be a satisfying conclusion to the person being rejected, but the alternative that the rejecter faces is facing abuse for their rejection, or a person otherwise persisting in the face of explicit rejection.
One could be honest and say ‘I’m not attracted/interested in you’, but that can be quite an awkward conversation, and lead to further awkward interactions in the future.