Additionally, in cases of a very large network - like Shotbow, Hypixel, The Hive, etc. where you connect to a central "hub server" that you can then join specific games and servers from - you may not be able to play with your friends.
The reason for this is two-fold: One, Mojang says that once you have access to a "server" (defined as an address you connect to in Minecraft) you have to be able to access any game or world made available by that server.
In Shotbow, we have many different games. Some are small (Light Bikes), and others are massive (MineZ - When in Rogue). Some, such as MineZ - also have paid-only worlds.
With the new rules in effect, we can't display these paid worlds in a hub that free players can access. So we would have to at minimum double our infrasturcture (more costs) and split out community in half (paying users and non-paying). So you can no longer hang out with your friends in the hub.
Even then, what happens in the paid worlds can't be shared with the free worlds - Any items, experience, or anything else gained is exclusive to the paid server. And of course, in order to increase the chance of money flow (so we can pay our bills), paid worlds would offer the best experience.
So any of your friends that pay for the server would have to be completely separated from your friends that aren't paying - including any actions they take in the game, and any experienced gained because of it.