In building a platform, credentials carry weight. It answers the question, "Who am I to write on this topic?" This is crucial for nonfiction writers, and I see a growing trend for novelists to assert their background.
For example, every fifth novel seems to be about the Amish—and some, I'm told, are grossly inaccurate. Agents and editors now ask what credentials they have to write about that population. Some of the authors have never met Amish people and base their work on novels they've read by others. That kind of second-hand research doesn't constitute reliable credentials.
If, however, you want to write fiction or nonfiction about something that occurred when the British took control of India in 1858, you would have to rely on second-hand sources. But you'd still have to prove that you did thorough research.
If you're doing serious research, a good idea is to discover the authorities others quote. That is, you need to cite the best sources on the topic.
Your responsibility is to prove you have the credentials (background, education, qualities) to write on your topic.
1. What kind of research have I done on my topic?
2. What more can I reasonably do to boost my credentials?