Inferior products prevail all the time. The free market is far from perfect. Especially when one product exploits negative externalities.
Yes, inferior products prevail from time to time, especially when those negative externalities you mention help consolidate a dominant position.
But social networks do not charge money. People are free to open as many blogs as they want. If they didn't when they were raging in the early 2000s there must a reason.
Reality is complex, especially human motivations. But to argue that blogs are a superior for the mainstream public to share themselves to an audience is a bit intellectually unfair.
Like... distribution?
Exhibit A being the QWERTY keyboard most of us are typing on right now.