Your website is your first employee, it works for you 24/7 for only one cost per year. Your website design attracts new customers from Google, Bing and Yahoo, educates those new customers on your services & products, then converts them into buying customers without your involvement, but to fulfill the order it'self after the order has been placed.
It's good to have social media channels, however you do not own those social media accounts, nor do you control the algorithms of those social media accounts. Therefore, you need to send all of that social media traffic to a relevant source that you own and control, that source is your website. The main purpose of all of your marketing strategies is to get those leads and prospective customers to your website, so they can be further educated about your services, choose if your services is the best fit, then purchase.
In today's market, a nice, well put together website is a sign of trust to a potential customer. After hearing about a new business, most people will just google the business and see how the website looks, if the website looks nice and has a contact number, most leads will just move forward into the sales funnel. Without a website, your business is pretty much irrelevant in your market, simply because most of your customers are shopping online now.