atomicpoet, 
Today, I decided to check if Usenet is still used by people for discussions.
Yes, it is.
Take a look at this screenshot for yourself.
Messages were posted to comp.sys.mac.advocacy today!
Is this a popular way of doing social media? Not at all.
However, it is persistent.
You can accuse Usenet of many things: lack of moderation, spam, aesthetic ugliness, etc.
But one thing you can't accuse it of is being dead.
Right now, Usenet is 43 years old -- and it lives!