Seo
I do believe if you have taken the time to comment on a post in a way that significantly adds to the discussion or provides the reader with further information, it is not unethical to post a backlink to your site.
We still utilize this process in our SEO efforts,but it is certainly not the only method we use.Commenting on posts is a valid SEO strategy. What is unethical and self-serving is simply spamming posts by placing your link without adding to the dialogue at all.