> Session data and any centralised auth check (banned user for example) are simply database calls

JWT doesn't make sense if your app can simply make a direct database calls for authentication check. But if your app is composed of myriad of microservices which aren't allowed to query the database directly and must call another service to access data outside the caller's scope, then yeah the only option is making the authentication service fast enough to tank all the authentication checks or use jwt which makes any microservice able to confirm authentication status without querying the auntentication service.

Which is another reason why I think microservice architecture is a giant waste of time and productivity unless you're google-scale.