You could certainly get away without some of the other stuff but, as another comment has mentioned, it requires some infra know-how. Like, you can't "just" use ETS as a Redis replacement without setting it up in a way that its data won't get blown away during a blue-green deploy.
There may or may not be “good” rationale. Could just be that most people using elixir are coming from other languages/ecosystems where all of that is normal.
Also in my experience, most of the time, the infrastructure team doesn’t know anything about elixir.
[0] https://dashbit.co/blog/kubernetes-and-the-erlang-vm-orchest...
You could certainly get away without some of the other stuff but, as another comment has mentioned, it requires some infra know-how. Like, you can't "just" use ETS as a Redis replacement without setting it up in a way that its data won't get blown away during a blue-green deploy.