I write a ton of config in a bespoke python config language and FAANG and there are definitely downsides to having logic in your configs. Config is supposed to be explicit and when you start iterating over lists and parsing conditionals, those layers of abstraction can make reading a simple config quite cumbersome. Additionally, each team will often write their own libraries which diverge from the standard practices furthering the stratification.

That being said, these config can get very complex and I can’t imagine expressing them in something even relatively friendly like yaml