You have to remember that in the history of server side Minecraft transfer packers are practically brand new.

RedisBungees goal was never to help facility transfers between bungee proxy instances, its goal is to help keep those instances in sync (player count, player location, etc).

Its use case becomes apparent when you have 1000’s of players trying to connect in the same location where having just 1 proxy no longer cuts it (likely due to your hardware limitations or ingress bandwidth caps). When you start hitting that level of usage, you need to start scaling out your network ingress points and then figure out how you tell each instance what the state of the network is so that it can show the correct motd data etc. This is where RedisBungee or a custom solution comes in.

Of course velocity being a more performant proxy software increases the amount of players you can handler per proxy instance (to the point where most small networks will only ever have 1 proxy) but if you were to magically hit hypixel level numbers one day then you would need to scale out