Not all website visitors are going to make a purchase or a conversion the first time they visit. That's why it's important to ensure you're getting your business back in front of them and persuading them to visit again.
A/B testing gives you the chance to optimise a certain element of your strategy based upon real data. You can change various elements, experiment with everything and see what brings the best performance.
LinkedIn has over 500 million users; it's full of business professionals and those interested in business. LinkedIn allows you to get in front of people you may never have before, and LinkedIn advertising enhances this.