Even if you is selfhost google, facebook & co still have a big influence over the traffic you receive, so alhorithm changes still affect you. For a book, other

Even if you is selfhost google, facebook & co still have a big influence over the traffic you receive, so alhorithm changes still affect you. For a book, other ways of advertising are effective, so you're reasonably independent. For news and other small pieces of content, it's much harder to avoid dependence on big aggregators.