As a web programmer, I always wonder: What should the printed version of a page look like? My personal opinion: an extra link and a page for the printed version, this is not even yesterday.
Habr went a different way: not to display extra information when printing - just an article and comments.
On the one hand, this is correct, comments are directly related to the article.
But on the other hand, I often send a page to print so that I can pay more attention to studying the material or save it to read later (in transport, for example). In this situation, comments useless ballast. For myself, I found two ways:
Print only those pages on which the text of the article. Required to carefully review the preview. On the last page we get the first comments.
Fix CSS on the fly so comments aren't displayed. We get a great print version
IMHO, it would not be bad if there was an opportunity to minimize comments to get a beautiful printed version. Or do not display comments in the print version.