[rmtech]

> So what's the criteria for ascertaining that a company, like Twitter, has a monopoly on speech

There's no hard criterion, but YouTube is a great example; it is so dominant in the video industry that either you use their service, or almost nobody will see your videos. Facebook is another one - it is now the only social network of its type, and also owns Instagram. If your content is banned from Facebook and Instagram and YouTube and deranked on Google Search, your audience reach will drop to almost nothing. Just two companies control the majority of speech on the western internet.

Twitter IMO doesn't fit into this pattern; it is quite good with free speech. Richard Spencer still has a Twitter account!