Employees are encouraged to "go dark" on social media. There's significant internal training on secrecy. Public association with the company is strongly discouraged. I'm using soft words.
Even a lot of companies that don't have such secrecy in their DNA don't necessarily encourage social media posting. And, frankly, a lot of employees look at the risk-reward of being active on social media, at least in a professional context, and decide it's not worth it.
I left after two years.