> Personally I'd add an application level hash to protect the integrity of the records but that's just me.

The durability is for being able to replay the stream, a hash will not let you reconstruct the original message(s).

If you just need ephemeral comms, making it persistent is indeed overkill. But reliability challenges often come up with seemingly ephemeral comms too – think streaming responses from an LLM. The last mile can be pretty flaky e.g. iOS will cancel connections when users background an app. Using a durable stream for persisting the tokens means a client can ask to resume from where it left off / from the beginning of the stream, and the data would be available without having to re-inference.