If you are in business, you should not rely on third parties to maintain contact with your customers. What are some examples of relying on third parties? If you store your contact’s names, email, and telephone number on your Linked-In account. If you direct your customers to your Facebook page instead of your own web site. If everyone who knows your business knows only an email address for you that is provided by Gmail. All those free services are provided by third parties who have no obligation to continue the services.
Are you prepared if Linked-In goes out of business? If you own your own domain name, you can point it to any web page, including a Facebook page. You can forward email addressed to email@example.com to your Gmail account. Not only that, if for any reason you do not want to continue to use Facebook or Gmail, you can forward the same domain name (that your customers already know about) to a new web page or email provider.