This is true but the companies choose how to build and operate these spaces, which includes things like moderation and what they promote. Part of what makes Facebook important here is that they’ve put so much effort into taking over people’s socialization everywhere with an emphasis on being where your friends and family are. The more toxic parts of the Internet used to be different places you had to seek out.

Given how profitable that’s been it seems reasonable to expect them to be involved in fixing it.