from my own experience, running stateful services in k8s is not easy and prone to errors.

so unless your devops/sysops/whateveryouwannacallitops has a lot of experience, it's just not worth it when things like RDS/ElastiCache exists.

i worked at a place that was 100% k8s, but all stateful things (redis, mysql, rabbitmq) were either hosted or in VMs.