Any history of chat networks needs to include BBSes, IRC, ICQ, and Google Talk (now Hangouts).
Not surprised, as i think MS was quite aggressive in pushing it. After all, the early version came bundled with Windows XP, iirc. And you were greeted with a signup/login dialog on first boot.
This is not that different from how MS pushed IE back in the day, or grabbed the office network out from under Novell's nose back in the day.
And btw, i feel to some degree MSN Messenger ruined the net. Before then there was thriving local IRC channels for the smallest of places. But come MSNM people started exchanging contact info for it, and the net turned "clique-y".
Had many memorable chats at "philosophy and absurdity" and "poetry shack"....
All gone....all gone...