With Elixir specifically, you have the option of clustering these things. We (fly.io) send messages between servers using NATS. This works well with geographica

With Elixir specifically, you have the option of clustering these things. We (fly.io) send messages between servers using NATS. This works well with geographically distributed infrastructure, messages are somewhat peer to peer. If we were using Redis, we'd need a round trip to a centralized server. And we'd need the internet to always work well. You can do a similar thing with Elixir and your own protocol (or the Redis protocol).