Commenting is one of Drupal's core features, provided by the comment module. After enabling it, comments can be allowed on a per content type basis with individual nodes being able to override the global default. The complicate thing about comments, however is not, how to enable them, but to limit their abuse. In an ideal world, one could assume all visitors to behave, but the reality looks different. There are many good reasons for and against allowing comments, that should be taken into consideration, before enabling the feature.
Arguments for allowing comments:
- Comments are a cheap way of producing additional content.
- Search engine users may discover a blog post because of a comment.
- Comments may start discussions, making visitors return, maybe even become subscribers.
- Comments may work as a primer for starting a social network of like minded bloggers.
Arguments against allowing comments:
- A comment function always attracts spammers.
- Comments attract trolls.
- Comments attract know-it-alls.
- Potential for legal trouble. A blog owner is also always a publisher and as such the first person, being contacted by the authorities in case of illegal content.
- Copyright questions: Who owns a comment and what may be done with it?
- Risk of exposing one's social network to datamining techniques.
- Posts without comments make the blog look deserted.
- Comments add more database queries per page and increase page size. Both resulting in slower page loading.