I use k8s, wouldn't call it simple, but there are ways to minimize the complexity of your setup. Mostly, what devs see as complexity is k8s packages a lot of system fundamentals, like networking, storage, name resolution, distributed architectures, etc, and if you mainly spent your career in a single lane, k8s becomes impossible to grasp. Not saying those devs are wrong, not everyone needs to be a networking pro.

K8s is meant to be operated by some class of engineers, and used by another. Just like you have DBAs, sysadmins, etc, maybe your devops should have more system experience besides terraform.