So, SMS did something similar and that excuses Simbin from offering unrealistic expectations? No to mention the situation it's not even similar. GTR3 was announced on 2011, when SMS was making NFS games. This is closely getting worse than The Last Guardian.
And no they don't have to post anything on the social media or be serious when they communicate with costumers. As a matter of fact, they could release the game without telling anyone. But of course, the game wouldnt be selling a lot...
They need us because expectations and marketing campaign it's essential on the success of a game. And it's not a matter of "they have to" or "they own us", but you can't ask people to take them seriously or say this is something normal.