[geospeck]

I've watched one of Rich Hickey's talk and at some point he brings that issue on the table, what happens when the receiver is not responding to the message.

He is advocating Queues and one of his arguments is that Queues decoupling the requester from the receiver. So you don't really have to worry about things like this by using a queue.

[1] https://youtu.be/ROor6_NGIWU?t=1955

[Fellshard]

That's abstracting in time more than in implementation; and it's primarily useful with stateful objects that are best reasoned about as a single, synchronous timeline (which most objects are). You'll see this pattern used in, say, Actor systems, as a queue-backed inbox.