Negative SEO was named such because the goal is generally to push things down, not up, as with standard SEO. NOT because it's bad or because something is wrong with it.
Negative SEO is also just as legal as standard SEO practices; it's NOT hacking. It in fact, has nothing to do with hacking.
Skunk Tech is the first and still ONLY SEO Agency to have the "balls" and admit that we use negative SEO in our campaigns, even though many, many agencies do.
We use negative SEO when it makes sense to do so. Just like you would employ any technique or business method when and if it made sense to do so. We also understand that if we push a website down two spots or push one over it by two spots, it's the EXACT same difference. You are not destroying or ruining anybody's business. Not any more than using standard SEO does.
We use Negative SEO because we have been developing these methods and techniques since 2014, and it just plain works!