Microsoft's Nate Clinton has used a bogus excuse to explain why Windows Update installs stealth updates without the user's consent. He writes in the Microsoft Update Product Team Blog:

One question we have been asked is why do we update the client code for Windows Update automatically if the customer did not opt into automatically installing updates without further notice? The answer is simple: any user who chooses to use Windows Update either expected updates to be installed or to at least be notified that updates were available.

Well, if Microsoft understands that a person wants to decide to install their own updates, then they should be respectful of that user's choice and be consistent with their policy. Being consistent means that they should tell the user that an update to Windows Update is available and that if they want it to continue to work properly, that this update should be installed. Maybe the user will decide to stop using Windows Update altogether, or maybe they will install the update. Either way, it should be the user that decides, not Microsoft.

However, this should come as no surprise. There is other evidence that these types of policies apply to other pieces of Microsoft software as well, including Windows Defender. In the End-User License Agreement for Windows Vista it states that after searching your computer for software, if Defender finds any "potentially unwanted software rated 'high' or 'severe,' [it] will automatically be removed after scanning unless you change the default setting." Where "high" and "severe," are undefined terms, and where the default behavior is to delete the software (instead of just quarantining the software and asking the user if they want to delete it). It gets worse. Later on in the same section they warn you that Defender may remove or disable software that is "not potentially unwanted software." In layman's terms, "not potentially unwanted software," is also known as "your software."

At least Microsoft stays consistent with one policy: keep the user confused and unclear on all policies.