Windows API is built on kludge of functionality, not performance. For example, GetPrivateProfileString [0] does exactly what you stated for files. Opens, parses a single key value, and closes. So much time and resources are wasted with the GetPrivateProfileXXXX APIs.
This function is provided only for compatibility with 16-bit Windows-based applications. Applications should store initialization information in the registry.
They literally provided the registry to solve this very problem from the days of 16-bit Windows. Holding it against them in 2025 when they have given you a perfectly good alternative for decades is rather ridiculous and is evidence for the exact opposite of what you intended.
This functionality is still used in software after 16-bit. It is even used by Skyrim software developers when it was "mark for compatibility by Microsoft". There is a project that hacked around this bad API [0]. You are going off the documentation wording versus real-world usage. Anyone that plays Skyrim today or in the future is still being harmed by this bad API.
INI files are 100% different than the Registry. I rather have an configuration file over registry entries because the registry is just another kluge of bad design. Configuration files are text files that are well defined.
Example would be the registry settings to mark a URL that it needs to run in IE compatibility mode because the source use old IE features that are now obsolete and don't even work in Edge or a modern browser. It should of just been a simple string array.
[0] https://learn.microsoft.com/en-us/windows/win32/api/winbase/...