What exactly makes you think it can't scale? Hacker News scaled from hundreds of users to hundreds of thousands of users and is still very high quality. Worse

What exactly makes you think it can't scale? Hacker News scaled from hundreds of users to hundreds of thousands of users and is still very high quality. Worse in some ways and better in others. Reddit scaled to tens of millions. Just because Twitter is run by people that can't scale it doesn't mean it's not possible to scale it.