Microsoft seems to have a history of picking very poor domain names.

Google does the same. withgoogle.com?

Right? If you asked me, I'd say that domain "microsoftedgeinsider.com" belongs to some Indian scamming call centre.

For what reason have they purchased that domain instead of hosting it under microsoft.com ?

Buying a domain was easier than dealing with the MS department of subdomains of microsoft.com?

I would have believed that if it were HP. Snark aside, it is unusual behavior coming from Microsoft.

I'm having trouble digging it up now but at one point there was a domain associated with promoting Exchange 2003 that Microsoft let go of. It was still linked from all their docs but the new owner had it redirected to a Youtube with a fly fishing tutorial. Strangest hijack I've ever seen.

Hosting things under microsoft.com is bad for security. One xss attack anywhere on the domain can steal cookies for the whole domain.

As a web developer, I only want to build to the security level my site needs, not the security needed for Microsoft logins.

They must own the .microsoft TLD.