This means that Microsoft is actively ignoring clear decisions taken by users, so if you do not want to be forcibly upgraded to a newer build of Windows 10, the advice is simple: avoid KB4023057. While this is something that you may feel uncomfortable having done for you, it is noted that "this update may try to reset network settings if problems are detected, and it will clean up registry keys that may be preventing updates from being installed successfully". What this means in practice is that Windows may run the Disk Cleanup tool to free up space, as well as compressing files. These improvements help make sure that updates are installed seamlessly on your device, and they help improve the reliability and security of devices that are running Windows 10.
This update includes files and resources that address issues that affect the update processes in Windows 10 that may prevent important Windows updates from being installed. It may take steps to free up disk space on your device if you do not have enough disk space to install Windows updates.
Microsoft explains that the update "includes reliability improvements to Windows Update Service components in consumer Windows 10". The update applies to many builds of Windows 10 - specifically 1507, 1511, 1607, 1703, 1709, 1803, 1809, 19 - showing just how eager Microsoft is to get more people upgraded to the latest version. Having made a conscious choice to avoid upgrading to the latest build of Windows 10, anyone installing KB4023057 will be disappointed to find that the patch ultimately results in build 2004 being installed.