why doesn't iconUrl accept local files?

```
    /**
     * A publicly accessible, fully qualified HTTP(S) URL to an ICO file, used as the application icon
     * displayed in Control Panel ➡ Programs and Features. The icon is retrieved at install time.
     * Example: http://example.com/favicon.ico
     *
     * Does not accept `file:` URLs.
     *
     * @defaultValue the Electron icon.
     */
    iconUrl?: string;

```