I think that if Facebook has some guidelines on hate speech and violent imagery it’s its duty to enforce them or renounce to have them and announce that to users. I enjoy using Facebook to keep in touch with my extended family and friends in different countries and I don’t expect to find violence or hate speech. People have a lot of places to express themselves that way outside Facebook. I think the owners of the website have the right to establish some guidelines if they want and users have to respect them. Control that with millions posting every day? almost impossible.
I’m Journalist and I’m for freedom of speech, but I don’t think that gives you freedom to deliberately spread lies or call for violence or denigrate human dignity. Precisely because of how I value freedom of speech I think is very important to work in my field with ethics, looking for the truth honestly with a lot of respect for human dignity. That usually gives you a lot of work, it is difficult and not very sensationalistic. It is not the easiest way to get famous, but is the right thing to do and gives you peace of mind.