The core problem, as I see it, is copyright.
Content must be hosted, and hosting costs money. So how is money going to interact with this system?
Copyright answered that question in the worst possible way. Copyright says that the content itself is the object with monetary value. To support that claim, copyright wraps every piece of content in a box, and says, "Whoever made this shall monopolize its value." In reality, only the box itself can actually behave as a discrete commodity, and no one truly creates content alone: all art is derivative, especially written media. Regardless of reality, copyright demands that we all participate in this delusional game.
So now everyone who hosts content is holding commodities. It's naturally advantageous to exploit the value of your commodities (you can reinvest your profit into actual value), so any business that does that will be more successful than the rest. Anyone who refuses to play the game will simply lose (or be prosecuted). So how do you sell forum posts and memes?
You don't. That doesn't make any sense, remember? You don't actually sell the content: you sell the box. You sell the warehouse. You sell the marketplace. This entire game is predicated on monopoly, so what's the most natural implementation? Vertical integration! Facebook and Twitter don't sell social networks: they sell social walls. What are those walls made of? Incompatibility. The best part is: if anyone tries to build a door into your wall, you get to sue them out of existence! It doesn't matter how broken or exploitative your business model is: if it is based on copyright, then it is guaranteed by law to succeed!
So now you own everyone and everything. How do you make money? By selling them to each other. In other words: advertising.
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But wait, there's more! Copyright answered even more questions: How do you stop people from misrepresenting someone else's work as their own? How do you stop people from sharing your secrets? How do you censor abusive material? The answer is to prosecute fraud and abuse, because those are already illegal. Right? Right? No. That would make too much sense. The real answer is copyright.