Free land is a land where I can live without someone threatening me with violence if I don't share part of the profits I make with my labour.

The freedom can be provided by the inhabitants of such land, either by getting weapons themselves or by paying some members of this community.

By this definition all land is free as you can go ahead, inhabit it and get weapons or pay some members of the community.

I'm struggling to understand what you're trying to argue, to be honest.

Not the same poster, but I think his point is:

Consider a world where society lived by the anarchist principles. In that hypothetical world, most people self-organized in a large group where:

- They decided to democratically appoint representatives that flesh out large-scale agreements and called it law

- They decided it is necessary to have people dedicated to securing the lands where they live from both internal and external threats

... and so on and so forth, until they effectively self-organized into the equivalent of our current society.

Is there any difference between that world and ours? Why can't an anarchist assume that this is what actually happened (there's some merit to the idea) and be happy to live in an anarchist world, our world?

This is one explanation. The question I have is more of the "what are you going to do when some people will get together and apply concerted violence to you (not dissimilar to the way the government works right now)?". I have not seen a single attempt to answer this in the few hundred comments. It appears most anarchists do not even realize this possibility even exists.

Right-flavored anarchism (eg anarcho-capitalism, cryptoanarchism) addresses this question directly - a plurality of competing defense companies that would be incentivized away from actually fighting as it would be unprofitable.

If you don't mind me asking, what is the difference with feudalism where plurality of land lords provided the same service?

Peasants didn't have much mobility between lords, therefore they were seemingly coerced. Would anarcho-capitalism as stated necessarily play out similarly? Who knows.

The core of anarchism is the heuristic of rejecting hierarchies and coercion. A negative doesn't make for a compelling mass movement, hence all the different flavors are attempts at imagining structures that could replace the current ones. They all have obvious potential failure modes, but the core remains - downsizing the structures of arbitrary authority.

This is exactly my impression too. E.g. the OP article begins with characterizing anarchists as out of touch dreamers: Anarchists are simply people who believe human beings are capable of behaving in a reasonable fashion without having to be forced to. Judging by the name of the site it appears to be a positive characteristic too, which adds to confusion.