Not everyone is a marketing expert or a salesperson. Many of my clients are small business owners who are just getting started with pursuing their purpose and are passionate about what they do... but that doesn't mean they know the first thing about branding or marketing or sales.
I've found that many of them are confused about the difference between those three business tasks.
That's fair. Why should they be an expert in something outside of their talents, skillsets, and experience? However, as a business owner, understanding the difference is necessary to put together a solid business and marketing strategy.