Why is Microsoft Not Blocking Bad Programs from installing?

Question

http://windowsitpro.com/security/microsoft-clarifies-commitment-antimalware-security

I doubt Microsofts commitment. I clean so many Windows machines with 3rd party tools that Ms could buy and build in to protect the OS. The fact the malware, adware, search redirectors, trojans and root kits
got installed into the OS because Windows does not check any black lists or do any heuristics before installing shows a level of sloppiness that is not ok and not professional. Everything he was infected with was well known to Google and the OS could have blocked with a whitelist web service.

They have had a few decades to master protecting consumers and obviously they do not take it seriously.

Answer 1

So does Windows 7. But a bad program will get installed if it uses social engineering to trick the user into supplying thinking they are installing something to improve performance and keep system safer.

Ideally some of these known baddies would be on a Black list and Windows 7/8 would warn the person not to install it or flat out not install it ideally.