Someone at MS made a fun IRC client. Thats it. It’s a WILDLY different world than 30 years ago and MS is a different company.
They released old code for those interested. Celebrate it.
They embraced the Internet; in this case IRC. This followed Bill Gates' well-publicised memo "The Internet Tidal Wave" a year earlier (http://news.bbc.co.uk/2/shared/bsp/hi/pdfs/18_06_08_internet...). It didn't happen because "someone at MS made a fun IRC client".
They extended the open IRC protocol with proprietary extensions hidden inside CTCP (Client-to-Client Protocol) messages to support "the fun stuff": https://github.com/search?q=repo%3Amicrosoft%2Fcomic-chat%20... (you need to be logged in to Microsoft's Github for code search to work nowadays.)
The outcome of this effort: Comic Chat was interoperable with regular IRC clients, but when two Comic Chat users connected, they could see richer interactions.
MSN was aimed at, well AIM, to the point where AIM used protocol flaws to block MSN clients. And it doesn't track that they'd just abandon IRC considering it was a period of absolutely massive growth for the protocol. It's more likely there was no intent to EEE IRC.
Why does it matter to today? It just makes your first sentence feel like a backhanded compliment.