Xbox uses Windows
Xbox uses DirectX
xCloud uses Windows and DirectX.
But you're telling me that game development is not universal across the entire Xbox platform, Windows, and DirectX.
And what are you basing your claim that there is no cross-development between Xbox and Windows on?
Have you ever spoken to any developer involved in this? Apparently never in my life.
I've spoken directly and personally with the Dev of Forza Horizon 5 and Diablo 4. He explained to me how easy it is to create a game on Xbox and port it almost instantly to Windows, or create it on Windows and port it to Xbox because they have the same architecture, API, and operating system.
There is no additional cost in making a game for Xbox and Windows or for xCloud because they all run within the same API and system.
Microsoft Defender is generally far from good for desktops, but Microsoft Defender for Business is probably about what you're talking about - and they're a bit different

Is there an Active Directory for Linux?
Other antivirus programs buy a lot of advertising to be mentioned in articles and on websites.
Microsoft doesn't advertise Defender, but other AVs have to do so to get people to install them.
If you are using RedHat Server with Red Hat Enterprise Linux PCs you get a similar experience to Windows Server AD.
The same thing happens if you use Ubuntu Server with Ubuntu Pro on client PCs.