Microsoft develops the OS...who better to also patch up and protect its own vulnerabilities...
Other VS work well but they themselves don't know what truly goes on in Windows...only MS does and that can make a difference when trying to protect its' security
I hear this statement a lot regarding to MSE.
But the fact they created OS, doesn't mean they know what to do with it.
Just simple example:
Internet Explorer.
Yeah, Microsoft know how to create OS, but it's other products aren't that great, are they?
Firstly for most users Internet Explorer lacks usability. That's why they are switching to other browsers.
IE still has the biggest marketshare but it's only because corporations where people are forced to use it as it comes with Microsoft forcedly aswell.
How many year it took Microsoft make IE less vulnerable browser?
Almost everybody agrees that IE versions below 8 where and are one of the less secure browsers.
So where was Microsoft then?
Even then microsoft was the one who created Windows, and they new evrything about OS and what's going on in the OS.
What was Microsoft doing when, Other companies like Opera, Google, Mozilla were able to make browser which worked on Microsft's OS and still was better, more secure and more comfortable to use then IE.
They managed it even though as you say, they didn't know what's going on in the Windows.
But Microsoft's knowledge of All aspects and behaviours of Windows didn't help them get their IE to the level of the browsers which are created by other companies, some based on open-source projects.
You know that's why claiming MSE will be great product as Microsoft knows best is Wrong!
As history shows other companies were better to make software (which out performed Microsoft's product not by only security but Performance, usability aswell) in Microsoft's own field.