Claim: the comment thread is as fundamental a form of expression as the essay
Reasoning: an essay is a path/list of ideas, whereas a comment thread is a "manypath"/directed-graph of ideas. So the claim can be reduced to "'graph' is as fundamental a data structure as 'list'", which is uncontroversial.
Comments
Yes, uncontroversial, unless and until you try to define the terms in a way that forces everyone into agreement. This is the basic flaw in arguments that rely on general acceptance of word definitions.