Though I'm no expert at this but these days negative SEO has also become a part of the search engine optimization. What this means is that some competitor can create thousands of bad links to your site causing your site to incur a penalty in search ranking.

Google has created a disavow tool for this but for someone who runs a blog and not super tech savvy may not know about it and regardless it is still a burden for anyone to keep up with all this.

Again, I'm not an expert at this and I'm doubtful that a billion dollar search engine can be tricked by such shenanigans but it may be something worth looking into. if your site traffic drops