Well in that case, it's all the ways that IDEs like to jank up whitespace, as well as the additional difficulty knowing 'context'.
With JSON it's fairly easy for me to know if I want to end my structure as well as the structure containing it, I can just type }}, and add the next element.
With whitespace you have to keep track of HOW MUCH whitespace, and trust me once you've got people who are entirely inconsistent with how much whitespace they use it becomes a huge PITA.
My point was the arguments are much the same for any human edited, computer parsed format. As for whitespace, you can set many IDEs to display placeholder markers if you want to go that route, it does help with visualizing horizontal alignment.
I find that paste/format on copy/paste with YAML can be kind of troublesome too though... I have an exception in my vscode settings file for that format, my default is format on paste and save.
With JSON it's fairly easy for me to know if I want to end my structure as well as the structure containing it, I can just type }}, and add the next element.
With whitespace you have to keep track of HOW MUCH whitespace, and trust me once you've got people who are entirely inconsistent with how much whitespace they use it becomes a huge PITA.