I think this is more a personal preference rather than something practical. As a counter-example, I've implemented Ansible-like syntax as a configuration for a couple of unrelated projects, and people like it because it is similar to Ansible, which is used for infrastructure management. I doubt I'd do that by writing a parser for Python-like configuration language.

Also, don't forget that yaml is way easier to pick up by non-python developers and people unfamiliar with programming.