The idea is not only to always adjust the response, but also to be able to elect when the response should be returned from the client code. So for example here the postRequest could request immediate termination - which means that on the earliest barrier check the framework will attempt to terminate. If we want filters to continue, but then Controller not to be executed, we can set it to 'beforeHandleRequest', and if we would only like to skip the postRequest filters but still get the controller output, we can do 'beforePostRequest'.