Re: Beware the E E E effect
"Embrace, Extend, Extinguish."
In this case I don't think that's the motive. It was likely cheaper to grab this off the shelf solution than customising Windows to do the job in the time scale in which they needed it. For instance, the Arm CPU Windows kernel version wasn't in production back then.
I wouldn't be surprised if this was replaced with a Windows kernel based version in future though. Windows does have advantageous network stack capabilities like native hardware offload support that Linux currently doesn't.
"In many ways Linux is like herpes"
They got rid of Linux hosts from Hotmail eventually. I wouldn't count on it never going...