When the file association Web service was first being developed, the programmer responsible for implementing the feature just scrounged around and found an old unused computer and set it up as a simple Web server under his desk, so there would be something to test the code against. That server happily churned away serving out file extension information, and when people asked for their program to be added, he would manually add it to the server. The server worked just fine, and like most things which work just fine, it was forgotten.
And then remembered once things no longer worked just fine.
I think it was during one of the beta cycles, or maybe it was RC1, when the quiet neglected computer went offline. I forget why, so let's pretend that the programmer unplugged it as part of an office redecoration project. Suddenly, the shell.windows.com service went down.
What? The file association Web service went down?
Everybody had forgotten that shell.windows.com was still running on a computer under that programmer's desk. It had done such a good job up until now that nobody gave it a second though.
He plugged the computer back in and watched the server bang out requests like nobody's business.
Wheels were quickly set into motion to transfer the file association Web service to a machine with a little bit more professional attention and maintenance.