I feel like the downfall of such an indent-level character is that it’s whitespace. If it was somehow visible by default, you’d run into a lot less situations where folks accidentally add spaces-indentation into a tabs-only codebase and it would also help make indentation changes properly visible.

Last week, I had to look at an Ansible codebase (i.e. YAML), where a colleague had introduced a block: statement, where then everything indented below that will have its errors caught. It took me about a minute to understand how the hell this construct works, because I did not see that the deeper indentation had stopped at some point. That’s just a waste of time for no good reason.