This is more than naive. As long as your software needs any kind of configuration, there is a need for configuration management. There will be access tokens, certificates, backend configuration, partner integration of various kinds, and monitoring and backup configuration and you will want guarantees that these are consistent for your various testing and staging environments. You will want to track and bisect changes. You can either roll your own framework for this or use Ansible/Puppet.

Whether you distribute your software pieces with tar balls, linux packages or docker images or completely orthogonal to how you tie these pieces to a working whole. And the need for configuration management absolutely increases when moving towards containerized solutions, not by the change in software packaging format but by the organizational changes most go through where more people are empowered to deploy more software which can only increase integration across your environment.

I see organizations that have ignored this because they believe this magic container dust will alleviate the need of keeping a tight grip over what they run, and find themselves with this logic spread over their whole toolchain instead. That's when they need help cleaning up the mess.

I’ve not seen PXE used anywhere that the DC wasn’t O&O (or essentially close to it). As that’s the exception to the rule these days, isn’t your premise a bit cavalier?

I’ve used PXE a lot in my past [0] to great benefit (well, more specifically iPXE through chainloading), so I’m not detracting from it, just saying it’s applicability is limited for most folks.

[0] I wrote “Genesis” for Tumblr which handled initial machine provisioning from first power-on after racking to being ready for deploys.