It always cracks me up to see an article using phrases like "on major platforms" and just casually ignoring the existence of Microsoft Windows.

The current (Vista and later) API for obtaining the special folder locations is documented here: https://learn.microsoft.com/en-us/windows/win32/shell/known-...

There is also a .NET API for this: https://learn.microsoft.com/en-us/dotnet/api/system.environm...

It annoys system administrators to no end to see applications writing their files essentially randomly all over the system.

Apps should use the roaming profile for user settings, the local app data folder for per-user cached data, the program data folder for system-wide data, etc...