Your website should be your business's window to the world...not Facebook. People come to your website because you offer something that they are interested in, whether knowledge, a service or product. Your website should be your main source of information. When you put up your own website, you control and own all of the content. You can control your user's experience. There is no constant stream of information that will distract your visitors and pull them off into other areas not related to you.
Don't forget that Facebook is a business and its goal is to make money. They are more interested in people paying for advertisements and boosted posts than anything else. Second, there is an algorithm applied to accounts to control how many people your posts are shown to. So, not everyone will see what you want them to see unless they frequently visit your actual page.
Up until now it was difficult to keep your website content fresh and engaging for your visitors. Not anymore. It's easy.