Opinions are subjective. Those can be right or wrong, depending on the context. And indeed, authors' opinions are likely biased because they're tied to their experience writing fiction.
However, it's also important to note that not all authors seek popularity; most are actually learning to write good fiction. Don't worry about popularity if writing isn't good enough.
And offering advice to authors shouldn't be seen as a recipe for success or popularity. Think of it as a form of caring for fellow authors. Isn't it better to care than to be indifferent?
@Assurbanipal_II Well, I also usually include my own opinion notes as the opinions of fellow authors learning to write. There are no absolute truths or recipes for success—just advice to listen to or ignore. At least I've answered to the best of my ability.