K8s is great way to easily deploy and scale services. As we leverage Kafka, a lot of applications fallback on Topics and KTables for storage.
Kubernetes with jobs, cron jobs, operators, secrets etc is effectively an Operating System for the cloud.
Definitely worth the investment to learn and practice.
I personally haven't experienced the issues the OP is describing. It might be that StatefulSets and PVCs are more stable now then when OP tried them. Of course using managed/hosted K8s makes a big difference.
There might have been a way to support our use case better. But this was managed service and we couldn't easily tweak every settings. But also, we didn't want to.
Our goal of using Kubernetes is to make difficult stuff easy. Not to make easy stuff difficult. And in our skillset and capacity moving stateful services outside K8s was easier, cheaper and more reliable.