I know this question is not directed to me but I will answer and hope you don't mind my opinion. The writer can compose a hub without the comment block but most likely it would be an oversight. Why? Because Hubpages is an interactive community and it is the conversation and comments that keeps the website lively and "thriving." Mostly it is the informative hubs that could sustain without a comment block but it is the controversial subjects that requires the lively exchange of ideas. In the case of the poem, I think that a comment block is not necessary unless the writer wants to read comments about what others thought of the composition of the creative writing.