Kevin A. Whitesides and John W. Hoopes have a fascinating article in Zeitschrift für Anomalistik (vol. 12, 2012) called "Seventies Dreams and 21st Century Realities: The Emergence of 2012 Mythology," in which they explore how the 1970s alternative culture helped spread a myth with little grounding in fact.
Although Ernst Förstemann (1906) did not link the event to the end of 13 bak'tuns in his commentary on the last pages of the Dresden Codex, he did find what he interpreted as evidence for belief in a Great Flood representing "destruction," "apocalypse," and "the end of the world.” This notion was further elaborated upon by Sylvanus Morley (19 LS, 1946) to a universal destruction of the world and a "final all-engulfing cataclysm." Michael Coe was the first scholar to tie the correlation of a future Long Count date to a universal event. He noted parallels between Mesoamerican and "Oriental" religions, including similar concepts of eras or kalpas. He noted that the Aztecs believed the universe had passed through four previous eras and that we were now in the fifth, destined "to be destroyed by earthquakes" (Coe, 1966: 149). Coe claimed, "[t]here is a suggestion that each of these [eras] measured 13 baktuns [... ] and that Armageddon would overtake the degenerate peoples of the world and all creation on the final day of the thirteenth" and that "our present universe would have been created in 3113 BC, to be annihilated on December 24, AD 2011, when the Great Cycle of the Long Count reaches completion" (Coe, 1966: 149). The shift from the catastrophic flood of Forstemann and Morley to earthquakes, a fate predicted in the 1558 Aztec document La Leyenda de los Soles, reflects Coe's beliefs about congruence in Aztec and Maya eschatology. Coe was undoubtedly playing on Cold War fears to grab the attention of his readers, hence his use of the term "Armageddon." However, what he neglected to anticipate was how his reference to a universal "annihilation" would be interpreted in esoteric and counterculture circles that had already associated the ancient Maya with the lost continent of Atlantis, ancient wisdom, and perennialist beliefs.
It continues to amaze me how a single writer, making a single claim, can set off a chain reaction that echoes down the ages as later writers repeat, expand, and misunderstand the original. Here, Coe is at fault, but his scholarly speculation would have been forgotten if Landsburg hadn't been casting about for new material to make a sequel to his adaptation of Erich von Däniken's Chariots of the Gods, which was itself a success because of Rod Serling, who only narrated the film due to the disaster that was NBC's and Universal's treatment of his Night Gallery, leading to its untimely cancellation despite strong ratings. So, thanks to the failure of Night Gallery we not only got ancient astronauts and eventually Ancient Aliens but also the 2012 apocalypse myth. Truly, this was the most consequential series cancellation of its time.
It's the law of unintended consequences at work. I for one think we'd have all been better off with more Night Gallery and much less apocalypse and aliens.