You would have way less media "journalists" making a fuss about what someone said on that social network and would have problems just getting it to be popular, let alone displace any of the big ones. It would maybe be possible with existing one but that's a ton of work and someone needs to pay for that work.
And it's entirely possible for smaller community to have that, but the advantage with this is small community about X will also have moderators that care about X so
* any on-topic bollocks can be spotted by mods and it is no longer "unknown language"
* any off-topic bollocks can be just dismissed with "this is a forum about X, if you don't like it go somewhere else
That's not a solution though since every for profit business is generally seeking to maximize profit, and furthermore we already knew this to be the case - nothing he is saying is novel. I guess that's where I'm confused.