The problem is
It's not unlike robots.txt, for those who are familiar with that command.
What it does is prevent search engines from reading URLs. It seemed like a good idea when robots were filling blog comments with spam links, but moderated links and Captcha codes have solved that.
Now what it does is rob you of a modest return for the energy you spent posting a comment: the more links you have, the better for your site profile, and lesser-used but helpful analytics like Google Blog Mentions and URL mentions are similarly diminished.
As far as I can tell, there are no such tags on this blog. This suggests that you should include your URL in your comment. As the blogger, I like it, because I can check out your work and understand your point of view better. Readers like it too.
What's strange is that blog platforms by the same company seem to vary. I have seen the tags on WordPress blogs, but they also seem absent from some WordPress sites.
This, if you didn't know, explains why some of your link posting appears in WebMaster Tools, and some doesn't. (Another reason is that the list is not thorough.)
I find myself feeling a little cheated when I follow a blog for a while, and contribute what I hope are some thoughtful comments, sometimes detailed, and then I notice they are not in WebMaster Tools. I visit the blog, select VIEW SOURCE, use control F for FIND to locate the link quickly, and discover
I'll still comment, but how do you feel about that? I feel a little bit of disrespect from the blogger, assuming they know what's happening.
I also wonder what would happen if lots of prominent blogs allow people to pile up links, and whether search engines would sort them out and keep people from going wild. I commented on a top 40 blog to help a friend, and I still get 1-8 visitors from it every day, six months later.
Also, putting your link in your comment helps you. We've got some thoughtful, savvy readers who write pretty compelling comments, but for whatever reason, most of you skip your link.
Maybe it's because working it in effectively requires some manipulation. Consider:
Sincerely,
Joe
JoesComix.com
compared to:
...That's my point: you can't count readers that way. On my comic, Joe'sComix.com, we use the conservative approach, and I find it more realistic.
Sincerely,
Joe
Fact: to major search engines, the second example will get you a link, but maybe just a sliver of credit for the first. Reason: Search engines like links in text, not in lists and signatures. (I could stand to re-verify a few of these items, but I have to turn my attention to other projects shortly.)
Because so many webcomics have blogs now, often on the home page (the page that tends to have the highest PageRank, and thus best link placement value), what has long been a blog issue is now a webcomic issue. Being in favor of transparency and fairness, I think blogs with