Text messaging, yes is asynchronous - but you don't know what the settings of the persons device are. They could have forgotten or not have quite hours set and now it is very much a synchronous notification even if it's not synchronous communication.
Sending delayed - again things happen. I would rather send a delayed message when I am in full control of the situation rather than possibly not the next morning due to any chain of events from weather, traffic, family, etc.
I feel like this comes from my philosophy of even if individuals are correct, it doesn't mean they are kind. We live in a community with individuals and we should compromise and balance things where needed.