There are different kinds of content writer in the world nowadays indeed. However, different content writers would have the same purpose ultimately. The purpose is to help businesses or companies to promote the products or services. In the past, the number of content writer was few but now, a lot of people could be the content writer.
It is because in recent years a lot of companies are set up on the internet and these companies would need to promote their business through the website. And the most direct way to promote the business is to hire some content writers to write the articles and post on their website to promote the products or service. This kind of work is commonly found in the internet world nowadays.
Professional content writer would need to deal with different topics because content writing job nowadays actually are outsourced and content writer may receive projects from different companies at the same time. Therefore, they must try their best to do research and write the articles.
Yes, the professional content writer would not write the articles without doing research. They would not write articles to cheat so they would always try to learn before they write.
Besides, professional content writer would try to make unique articles. They would do research and find useful information. But they would not copy articles from the others. It is because they have their unique writing style and they would have the skills to write on their own. This is the reason why they would be hired.