No, they absolutely do not. Nor do they "control the perception of billions of people." That's just fear-mongering hyperbole. You might have an argument that social media influences the opinions of billions of people, but then you have to take into account the deluge of inputs most people receive from multiple sources online and off, and realize that the total influence any one social media platform has is not that significant. This isn't the world of a few decades ago where many people's worldview was informed by only three tv stations and one newspaper - and not even in that world did the media control people's perception.
When Twitter can levy taxes, field an army and a police force, declare Facebook illegal and bomb their campus into smoldering rubble, and coerce people outside of their platform to obey the laws they pass and enforce through their monopoly on violence then they might have something approaching the power of even a small nation. Being able to ban people from your website (and your website alone) is not equivalent to nation-state status.
>It's probably helpful that we start thinking of them this way and move toward some kind of equitable regulation.
No, it's not helpful, it's propaganda. It's the rhetoric of the modern form of the Red Scare, except now the "communist conspiracy" is running social media instead of Hollywood.