I disagree:

    good:
      - a
      - b
      - c

    bad:
      - a
        - b
      - c

Obviously when I show you this, it's clear that b is incorrectly indented, but in a real file, this can be a nightmare to figure out. Particularly if the entries are nested, or tab characters are involved.

Meanwhile, the error in JSON is way more obvious:

    {
      "good": [
        "a",
        "b",
        "c"
      ],
      "bad": [
        "a - b",
        "c"
      ]
    }