Questions about data persistence

[eSPiYa]

I'm trying out this workflow core project for microservices orchestration, and it can handle most of possible implementations and scenarios we can think of.

Regarding data persistence, why is it needed? What I can only think of is a feature of auto-resume in case of crashes or restarts, but I can't find any mentions of this. I was able to find a mention of resume but it seems it will only work on suspended workflows. Are interrupted workflows due to crashes or restarts included on this?

And in case I scaled out the orchestrator and used Azure Service Bus or RabbitMQ for queueing, is data persistence required for this?