The teacher/student relationship is definitely a hierarchy, and one of immense power disparity, yet it is not coercive.
We did have markets during feudalism. And feudalism plundered those markets, as all government systems do. Feudalism obviously wasn't capitalism. Feudal lords plundered land, food, and money. So do governments and their corporate cronies today. But this is all obviously in opposition to Lockean property rights and free trade, even though that is also commonly called "capitalism."
I don't know what world you live in, but if one person had all the knowledge, I'd see your point. This is 2019, we have the internet, and we have millions of people willing to teach. Your fantasy scenario of teaching being a natural hierarchy doesn't make sense in 2019. Maybe if it were 1208, maybe, but this isn't a Minecraft server that we refreshed a week ago, this is the real world.