These two things aren’t mutually exclusive. You can be an expert and also a commodity. Expertise just means that your commodity commands a higher price, and even that’s not guaranteed.
I would regard myself as an expert writer and editor. I’ve been a media professional for 15 years (20+ if you count my college journalism).
But there’s the issue of supply and demand in the labor market. There is a glut of people who write or want to be writers.
Then there’s the hegemony of certain ideas and viewpoints. If you’re a leftwing writer, as I am, in a country where the center of gravity is far to the right of most countries in Western Europe, then your pool of potential readers is smaller.
Of course, you might suggest that I become a content writer or some other work that has more commercial value, but that just underscores my basic point about the commodification of labor and the disciplining of the market.