Hello, you might not know, but IT also is subject to fashion. Not the one based on fabric, but fashion of format, in particular how to save text.
Long time ago it all started with Comma Separated Values (CSV). Format that is still very much actif, thanks to Excel and databased.
For config file the ini (from windows) format was quite standard
Then came XML as a formalisation of HTML. XML was more flexible and allowed for more flexbility and a simple way to navigate the data, in exchange for a lot of additional text and an almost impossiblity of bein read by humans.
Now we have YAML for configuration stuff and JSON for return data. They are very different, can be used intechangeably (yet not easily) and require a different set of knowledge to be used.
Each data format provides improved capabilities, but such a mess makes it hard to do some programming.