I will not describe the situation fully, here is a little example for clarity. Some people have JavaScript disabled (for whatever reason). The site has three sections (article, feedback form and comments). Without JS enabled, the feedback form and comments will not work, but will be visible to the human eye. He may try to interact with them (fill the form, send a comment) and nothing happens, he will be nervous. Not to make him nervous, and wanted to hide styles using these blocks in moments of lack of support for JS, but a thought a definite answer to which I give a loss.
Idea:
If there is no support for JS, hide unnecessary blocks and then there is the bot search engines — JS as he is disabled and he will not see a feedback form, no form of review and may consider this as hidden content, which, in the opinion of search engines is nothing but a one way influence on the ranking of websites in the results with all the attendant unpleasant consequences. On the other hand, I personally, would regard such action by the owner of the website as concerns about the user — hide, with which he cannot communicate.
Here, sitting, thinking, and the answer did not find. May be knowledgeable and experienced in web design and search engines people will share their opinion on this issue?!