But... Why?

For a long time, CNet's download.com provided a fairly respectable place to get software for Windows. It served as a mirror network, and as mentioned in another comment, sometimes as the semi-official download site linked from the official site. It also had relatively reliable links, unlike vendor sites which reorganize their long unreliable URLs on a whim. Some of the Open Source projects I've worked on used download.com links when they needed to reference Windows programs people might need (generally the kinds of utilities that Linux users already have readily available, such as disk utilities). And until these recent incidents, it provided a safe place to download software without expecting to get something nasty along for the ride.