Yes, it is one of the methods used by Russian government to silence the opposition. Though the platforms are usually privately owned, they all 'independently' decide that some content can't be allowed on them.
This is not true. Russian government does not dictate FB and YouTube (which it does not own), and they would have to force ISPs to block these sites if they wanted to ban the content. I doubt ISPs would ban them themselves.
Do not be so fast with 'not true' claims. Russia has at least three social networks, each with audience bigger than russian audience of Facebook and Twitter combined. All three remove anti-putin groups, etc.
the third one is Moi Mir (https://my.mail.ru), an extension of by far the most popular email service in Russia. Mail.ru corporation actually owns all three of them.
VK absolutely does remove anti-putin groups and events. [1]
You can't attack other users on HN like this, regardless of how right you are or feel you are. Please review https://news.ycombinator.com/newsguidelines.html and stick to the rules. Burning this place down is not an option.
Edit: given that your recent comments have been this shockingly abusive:
... I've banned your account until we get some reason to believe that you want to use this site as intended. That level of abuse is deeply not ok.
No, I'm not siding with liars-fascists-traitors. We'd ban any account that posted this way. Being right doesn't give you any excuse to behave like this, and no matter how wrong your enemies are, it doesn't give you the right to destroy the commons. It's not in your own interest to do that either, but that's another story.
Same will happen with the US. Sad.