In memory caches have scalable concerns and require sticky load balancer. You'd need to decentralize the cache (eg create a db for the session information) to allow horizontal scaling of services so this approach is generally considered old-school.

JWT has its own slew of problems, most of them are temporal (eg invalidation of all sessions), usability (eg short expiry), or additional security vectors (many poor JWT implementations, accidentally authenticating invalid tokens w/o signing, careless storage of readable values)