@cloudtrapezer I think you got this wrong: “But under capitalism, the product of workers' labour, whether physical or intellectual - news articles, lesson plans etc. belongs to the employer… .” If this is explicit in an employment contract,
you are correct. However, absent an explicit contract stipulation, development of intellectual property and its subsequent ownership, often becomes a matter of litigation at least “under capitalism.”
Socialists, and Communists, generally oppose any form of private property rights, including intellectual property, which nicely eliminates the existence of Intellectual Property (IP).
As for publishing your IP, it is often the case that you are required to relinquish you IP rights in order to be published. This is not universal and depends on the publisher’s policy. I developed a new approach to determining and calculating break even for complex businesses, was published but retained the copyright. Subsequently, I agreed to allow use of my method in an accounting textbook as long as I was given attribution.
About 40 years ago I came up with the idea of building a numeric key pad into computer keyboards. Being an accountant, and the Corporate Controller, I insisted the number key be arranged like an accountants 10 key adding machine instead of like a telephone keypad. It cost more to do it that way as the keypads had to be redesigned to fit into keyboards but you, and the whole world use it.
“Copyright was invented by and for early capitalism, and its importance to that system has grown ever since. To oppose copyright is to oppose capitalism. Thus, Marxism is a natural starting point when challenging copyright.”