Attributes are intended to hold metadata, not data. It's not the fault of the format if someone chose to use it in a poor way.

You also need to distinguish the format itself from the various libraries that may be available to parse/process it in a given language. It doesn't always make sense, even when it's an option, to let the tail wag the dog and choose a language just because it has a nice library for something.

> Furthermore parsing JSON or YAML gives you the basic data types like lists and dictionaries

Well, maybe some library for some language does that, and if that is the language you are using, and that is all you need, then I suppose you are in luck. More generally you may want to use a format like XML or JSON to hold user defined types, which rather levels the playing field since there are few good libraries for this in any language,and you may need to roll your own (been there, done that).