[absolute]

it really has nothing to do with server speed. It is more dependant on the speed of your connection. And you think you could send a map to 1000 people at once? I normally dowload from servers at atleast 100-200kbps. Let's say the upload is going at what i would consider slow. A modest 50kbps
50kbps*1000 uploads = 50,000Kbps = 50MB/s upload required.
That's also not including the upload for the actual game itself.
I don't know about you but I don't think my 1.5MB/750Kbps adsl connection could handle that.
And to rent a server on a good line that could handle that much at once...you'd be looking at a pretty large sum of cash dude.

What they should do though is enable to map uploading but have a paramenter where you can set the max uploads you can allow at once. Even my connection could allow uploading one map at a time at a good speed without any ping/packet loss.