Prior to the 1980s, an economic way to process metal sulfide ores did not exist. Thus, these types of ores were discarded with the mine tailings. Developments in the 1980s by pioneers such as Dr. Richard F. Hewlett and others brought new leaching methods and technologies to this field, such as the economic production of Nevada’s Carlin Trend.
Other than the BS about no way to process sulfide ores prior to the 1980's, you pointed out that Mr. Hewlett, the so-called "pioneer", was slapped with the following from the State of Arizona Board of Technical Registration:
C99-044 Richard F. Hewlett Nonregistrant Engaged in the practice of geology without the benefit of registration in the State of Arizona. Assurance of Discontinuance from engaging in the practice of geology, offering to practice or by any implication holding himself out as qualified to practice geology until he is granted registration; advertising or displaying any card, sign or other device that may indicate to the public that he is a registered professional geologist, or is qualified to practice geology until he is granted registration by the Board. Civil Penalty of $2,000.00