It's not just you. Maybe FB is not an example of brutalist design [1] [2] because it's more polished that true brutalists are. It's just a plain vanilla site. Instead of thousands of different layouts on myspace and even on blogger, it's a one size fit all design. A white and blue page should be enough for everybody, and it seems it is, especially when it has the size of an app on a phone. Remember that the vast majority of its users didn't have any web property before their page and feed on FB. They don't find anything missing.
[1] http://brutalistwebsites.com/
[2] https://www.washingtonpost.com/news/the-intersect/wp/2016/05...