I mostly agree with you that using current tooling seems like patching holes constantly but it's getting much better with sandboxing and automation is key and of course, it's not for everyone but can provide lots of benefits with "low" effort.
There is a Kubernetes Working Group where the definition and implementation of soft multi-tenancy and any feedback is welcome.
Thanks Alex! Pau here, please do not hesitate to contact us if you are interested in our platform.
Our mission is to allow users to benefit of kubernetes whithin seconds. We take care of ingress, SSL certificates, backups... so you can focus on what really matters.
We are going to bill by resources/minutes wich is really interesting for CI/CD where you need a real cluster intead of KinD.
We are going live in a few days, join our slack or email me for feedback :)