WriteFile and lpNumberOfBytesWritten << Back

I was developing in VS 2022 on Windows 10 and I got a snippet of code from CoPilot that looked like this

WriteFile(hFile, lpByteArray, 512, NULL, NULL);

It caught my eyes because I have used WriteFile many times in the past and I remember the fourth parameter (lpNumberOfBytesWritten) is NOT an optional parameter. So I consulted MSDN, sure enough it says

BOOL WriteFile(
  [in]                HANDLE       hFile,
  [in]                LPCVOID      lpBuffer,
  [in]                DWORD        nNumberOfBytesToWrite,
  [out, optional]     LPDWORD      lpNumberOfBytesWritten,
  [in, out, optional] LPOVERLAPPED lpOverlapped
);

Still somewhat skeptical, I tried passing NULL for the fourth parameter, it worked like a charm on my Windows 10 machine. I quickly forgot about the entire thing until I was testing ListViewExporter on my Windows 7 and Windows XP machines. My program crashed spectacularly on both OS. Long story short, I tracked it down to WriteFile being the culprit. Apparently I fell victim to the LT;DR problem. At the section where MSDN explains each parameter, it has a remark for lpNumberOfBytesWritten

[out, optional] lpNumberOfBytesWritten

Windows 7: This parameter can not be NULL.