First, it's very strange that an antiparasitic like ivermectin has become known among mainstream laypersons.
Second, those articles are from the 80s, one is nearly 40 years old.
Third, various antiparasitic medications on the market for dogs contain ivermectin (e.g. Heartgard, Iverhart, and Tri-Heart) - these uses include the prevention or control of hookworm infections.
Finally, when the original article mentions "three types of drugs" to combat parasitic infections, they are referring to the benzimidazole, avermectin/milbemycin (or macrocyclic lactones), and tetrahydropyrimidine classes of drugs - where ivermectin belongs to the avermectin/milbemycin (macrocyclic lactones) class of drugs. With that said, ivermectin-containing compounds are actually a notable part of the research.