> What’s wrong with YAML’s arrays?
That there are multiple ways to define Arrays: "- item", "-\n\titem", "\titem" or "item, item" for starters. Parsing YAML into Arrays requires context of its surroundings.
Without the previous context, you cannot know what type of data you're parsing when you are at a "-" at the beginning of a line or a "," in the middle of a line.
This is just unnecessary parser complexity and human ambiguity in my opinion.
As a question to you in case you disagree: What happens when you write down an indented/nested "\t- name: John, Doe"? It's pretty much unpredictable without the previously parsed data structures or their history in YAML.
(I don't wanna start the discussion of "<<" and how it influences the parsing context of YAML data structures. I think the merge key also has no place in a data serialization format.)