Should website users be able to delete their content?

As the title suggests, my question is: Should website users be able to delete their content?

What are the pros and cons of giving the users the option to delete their own comments and content (for example forum topics) on the website?

One of the downsides I see is the SEO impact of links that point to non-existent pages if the user removes their content. On the good side, users are able to remove accidental posts.

Similar topics have already been discussed here, but I was not able to find a question and answer that would directly address this issue.

EDIT: I am talking about regular forum system with topics and replies (comments) or cases of blogs where users can post comments under a blog post.