Yes, you are correct. My exact question is Proxy server vs Regular server when the backend is running Exchange server.
Setting up systems for clients can sometimes be confusing and trying to weigh options can be time consuming at times.

Modes used on setups is normally always Firewall mode with either Proxy or Full SMTP Server. So can we get summarised advantages apart from the ones listed earlier?

Deprecating the feature as stated on: https://xeams.com/SwitchingProxy2Regular.htm doesn't really show its disadvantages or its issues.  It could simply mean no more work is being put into the 'code' which is still perfectly functional, etc. Windows Server 2016 is still fully functional amidst missing some of the latest cloud features. 

Thanks!