Hey!
As you stated in your other post, Adobe does not provide this capability. While there are options to copy between environments and access control, there is no automation integration directly for e.g. QA and no version control.
I know that this has been done (I was not part of this though) and provides real advantages when looking at security perspective, as well as being able to maintain a complex setup, where manual copying will likely lead to human errors and can cause serious challenges. Leaving dev to allow manual changes is in my opinion a smart choice as well, since it should be as flexible as possible.
Manual changes in files however are also something that can be quite a complex part, as you well put, and each environment has it's own IDs for all of the Datasets, Datastreams and what have you, so making sure some values stay within each environment, while others are copied adds a bit of complexity. The good part is that when creating something new, like a RTCDP integration, you can create it in UI within DEV and see what the configuration or changes in it look like. Overall as I've understood, AEP APIs still house options that are not available in UI, so from this perspective there is nothing holding one back from creating such a process.