Many of them don’t even allow it to be a hidden file—they just require a fully unhidden “tool.yml” file sitting right there in the root of your project.

I love this. I hate when tools only allow hidden config files. I want to know where the config is—my teammates should be aware of where the config is. I don't want to be tricked into thinking there isn't a config file in a directory.

I actually have alias ls='ls -A' in my bashrc so I see everything.