It’s effective, but not in the way that you would expect.
A lot of people are under the impression that they just fill out the comments section in a typical WordPress blog, and they get automatically rewarded with a backlink.
While you can get away with automated comment approvals using tools like ScrapeBox, they're all no follow, and this pretty much destroys the value of those backlinks.
The better approach would be to find niche-specific blogs and truly participate.
Get on the radar by sharing valuable information that truly addresses the topic of the blog post you're commenting on.
Do this several times with a blog, and call out the blogger.
If you don’t agree with what they have to say or you have additional information, present that info or opinion in a way that would build respect for you.
And you don’t have to drop a link.
Eventually, you will be viewed as an authority because you bring something valuable to the table.
The value of comments is not so much the backlinks that they can produce, but the doors that are opened by your credibility because you're actually contributing something that the blog post either overlooked or is simply denying.
This creates the kind of valuable conversation that comments sections are supposed to host.
Once you become credible, you'd be surprised as to what kind of guest blogging or collaborative blogging opportunities would be available to you.
This is how you build a solid brand!
I know this firsthand because a lot of the blogs that I used to work on on a freelance basis are now big names because of the fact that the content that I shared through comments actually maximized the value of the blog posts that they are on.
