Fewer and fewer people use a phonebook to find the information they need. In many parts of the country phonebooks are no longer delivered to homes and businesses. Many use some form of internet search either with a search engine or on a smart phone. If you are still counting on the phonebook, newspaper, or radio you have some catching up to do.
Websites can and should provide valuable information to visitors. By doing so, you establish your expertise and therefore build trust among your visitors. A website that is done well builds credibility for your brand or organization. When people find your material valuable and helpful they are likely to keep coming back.
Your website is available twenty-four hours a day in nearly every part of the world. You can reach potential customers across town and around the world. No other medium offers that kind of exposure. Think about what that level of advertising is worth to you. If you are reaching that many people it is worth taking the time and effort to do your site well.