Black hat SEO techniques are mostly adopted by people who want the changes in SERPs very quickly and for short period of time. But these are spam techniques and Black hat SEO providers often fail to notify the client that they use spam techniques to achieve those rankings.
Link building is not a new concept, nor it is dead. Some time ago, it was the heart and head of SEO. With new tactics to trick search engine to put one's website on top, link building changed its form to link stuffing. And as a result came under black hat SEO.
