I think you're asking the wrong question.
Because at the end of the day, it doesn't really matter whether the comment is made by a flesh-and-blood human being or by software.
If the comment is made just to get links, you're missing the bigger picture.
You have to understand what comments are really all about.
When you comment on somebody's blog, you're supposed to actually share your expertise.
You're supposed to be part of the community that is coming together to come up with a group solution or to encourage each other.
In other words, you are building credibility and authority.
So if you approach manual blog commenting from that perspective, don't be surprised if you get more guest post backlinks and more joint publishing opportunities.
I suppose the better term for this type of commenting is relationship outreach through comments instead of manual blog comments.
It's going to take a lot of time but if you are taking rifle shots at the biggest and most legit blogs in your target niche, they should be all worth it in the end.
