Well, the first use case would be the ability to easily host and deploy the server. For instance, generate your own assets and have a private server.
Second use case would be when someone with protected assets wants to use the game for commercial reasons.
Third is ease of server deployment locally if you're only working the client, the server is just "there" for you.
And you can, without too much effort, run a Dockerized linux container on Mac or Windows. This means a standardized build can be shared by teams.
Not passionate about it, but it's been extremely helpful to me. I build big, complicated systems and I like to isolate the parts.