CRDs and their controllers are perhaps the reason Kubernetes is as ubiquitous as it is today - the ability to extend clusters effortlessly is amazing and opens up the door for so many powerful capabilities.

> I don't want to write a Kubernetes controller. I don't even know why it should exist.

You can take a look at Crossplane for a good example of the capabilities that controllers allow for. They're usually encapsulated in Kubernetes add-ons and plugins, so much as you might never have to write an operating system driver yourself, you might never have to write a Kubernetes controller yourself.