I guess a late answer is better than no answer.
From my understanding, you would use these classes to establish a connection between different instances of the engine, so they can communicate with each other without officially connecting through normal Unreal networking. So this is mainly useful for party or lobby systems, like the lobby of the OnlineFramework plugin or the party in the OnlineSubsystemUtils.
I can’t however tell you how the lobby and party beacon’s should be used. That’s what I am trying to find out and that’s how I stumbled upon this old post.