Yes and no, depending on the reactive implementation. Using Reactive Spring doesn't help much if we just simply replace the normal HTTP communication by a Reactive Spring communication. Responses of those communications would be handle by a callback in client side anyway.

I think when we intentionally use request-and-response communication, we want it to be synchronous (e.g. bank transaction), then the sever should be optimized and try to response to the request ASAP instead of sending the response to e.g a queue.