This law is true in some cases, but I think is too often used as the tech industry's version of "first they ignore you, then they laugh at you, then they fight you, then you win". The argument is that, sure, a technology's promise may have not panned out, but under Amara's law, we can expect a commensurately massive impact later.
As Carl Sagan pointed out, "…the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses." The same applies to technologies. The fact that a technology has shown slower-than-expected progress is not a foolproof indication that it will eventually have massive impact. It may just not be as useful as it initially seemed, or may even be supplanted by a completely different technology.
As Carl Sagan pointed out, "…the fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses." The same applies to technologies. The fact that a technology has shown slower-than-expected progress is not a foolproof indication that it will eventually have massive impact. It may just not be as useful as it initially seemed, or may even be supplanted by a completely different technology.