>Say I build a conveyor belt (the "means of production"), and Bob and Sally and whoever come by and use it. Eventually I pay them to make certain things. This is a problem? And it should be stopped? And what's the mechanism to stop it?

I think a self-described ancom would answer that as soon as you built the conveyor belt, it became communal property. Whether that is because you (as a true believer in the principle of not owning the means of production) ceded it to the workers, or because some democratic resource-allocation advisory board members came by to confiscate it, would depend on the ancom. Another possibility is that guilt and cultural conditioning would be the motivating factor. In an ancom society that was sufficiently established and had been operating for a few generations, people might be culturally ingrained with the idea that property ownership is evil, and therefore the thought would not occur to them to keep the conveyor belt for themselves. (If you haven't read *The Dispossessed*, by Ursula K. LeGuin, it does a good job of carrying out a thorough thought experiment with regards to the multi-generational left-anarchist society. The society in the book is something of a mix between anarcho-communism and anarcho-syndicalism.)

>but I don't get the way they consider voluntaryists to be their bitter enemy or something.

I think I can explain it. Whereas ancaps generally consider anarchism to be more-or-less synonymous with voluntaryism, ancoms do not. To them, anarchism is the "logical" outcome of Marxist communism. They consider themselves communists first, and anarchists second. In fact, there is a growing trend among them to self-label as "communist anarchists" in an attempt to put the most important descriptor first. In order to reach the anarchism, they have to go through revolution and seizing the means of production and eliminating their philosophical detractors and a bunch of other steps that could not feasibly be done in a voluntary way. Also, they object to voluntaryism on the grounds that it is predicated on the concepts of self-ownership, which they believe to be impracticable, and property rights, which they believe to be unjust.