With many services, after a certain size you begin to need tools to curate the content on the network, separate signal from noise, etc. But in a perfect world these could be handled and I think your statement would remain true.
For example, most forums begin with a small, dedicated user base that mostly knows each other and act in good will, but as the userbase grows all of these aspects fade as the Eternal September/tragedy of the commons effects take place. It's easy to see with the progression of subreddits for example, since they are created so often and can grow to very high subscribed counts, you get to see this pattern repeat pretty often.