If it was code, an indentation error would often not compile or show errors or fail tests.
Configuration in YAML is much worse: most of the time an indentation error goes undetected until an application starts misbehaving.
Significant whitespace is perfectly ok for code but a huge footgun for YAML
But I find it incredibly annoying to estimate indentation when lines are wrapped in an editor (or webpage). Or, to a lesser extent but still throws me off, when multiple blocks end at the same line. Or when pasting blocks into another block, and having to double check to make sure the indentation was carried over correctly. I like editors that visually show indentation characters.
Or, NODE <name> .. END .
it makes a difference on how it is parsed, so it's more than a devs preference
Personally I mostly use indent to read code, so requiring that the indent matches the semantic nesting makes it much easier for me to understand.
I get the original was talking about client facing config files. I'd rather see INI style config files personally.
If you're writing ugly code, braces or spaces won't save you. Just don't write ugly code.* Write it like the next person to view your code is an axe murder that knows where you live, so don't make them mad. You can minify later.
*I'm ignoring Perl, as it's always ugly