That is nice in theory and I agree it should be done wherever possible but lot of the time business logic will require immediate synchronous response to be retu

That is nice in theory and I agree it should be done wherever possible but lot of the time business logic will require immediate synchronous response to be returned as a next step in workflow will execute different branch of logic based on condition/result returned from previous microservice and the frontend / consumer / app will need immediate confirmation about whether action succeeded. Even in such cases you might want to move bulk of processing to asynchronous queue based system but part of the logic might need to be executed synchronously (authorise credit card payment, you can process the payment asynchronously later, perhaps in bulk cron jobs like Apple Itunes does it but initial authorisation which decides whether purchase is successful must be synchronous).