As I said, I have never seen anything I would consider extremist myself. Though from your reply, I get the feeling the issue could be an unreasonably broad definition of extremist content on your side. That or I just happen to not visit games with such discussions.

I am a big GOG enjoyer myself, but when I need to use steam for anything, I have never encountered such content. Perhaps there is such content in private or otherwise not very visible spaces (such as user profiles), where they will not get reported, but that is true for any site with user content. I call BS on this being an issue.