JSON was popularized by web browsers, yet some people use it for configuration for system desktop apps, which have nothing to do with JavaScript. If usage of JSON is not a problem, then why popularization of INI by DOS+Windows should be a problem?
If you think INI files were a blip on a radar then you might not realise their real popularity. They even have support by the operating system api (WINAPI had support for INI natively, ReadPrivateProfileString). Unless you say that they were a blip on a radar on Unices in the 80s, then I probably would agree.
By the way,
> as the Unix world had plenty of file formats and tooling for such formats before then, and the Linux-based operating system world had been busy cloning them all for years
And that was probably a good motivation to use something established and standard, like an INI format.