Gone are the days where having a website was considered optional for a business. Today it's expected that every business will have a website, and for good reason!
Your website is (or should be) the primary source of information about your business, and it's the only place online that you have full control over. On any other platform, your business is subject to the rules and business practices of the platform you're listed on. This may mean that you're not allowed to publish certain information, content may be limited in length, or you may even have competitor's ads shown on your listing!