I think people pick new tooling not because k8s lacks horsepower, but because running per-user filesystem-backed agents on k8s forces you to build and maintain a surprising amount of glue code. Newer platforms put versioned mounts, local-first dev cycles, secure ephemeral runtimes, and opinionated deployment so teams can focus on agent logic instead of writing Helm charts and CSI gymnastics.

If you repurpose k8s with ephemeral volumes or emptyDir, a sidecar, you'll likely get predictable ops and avoid vendor lock-in. Expect more operator work, fragile debugging across PVCs and sidecars, and the need to invest in local emulation or a Firecracker or gVisor sandbox if you want anything like laptop parity.