All kinds of knowledge has been lost to poor record keeping, dark ages, warfare, and periodic bouts of anti-intellectualism (heresy and witchcraft!) over the course of history. Lost technologies are more easily explained by poor information management than alien benefactors.
The library of Alexandria is a good example. An institution dedicated to being the grandest collection of knowledge in the ancient world, and there's evidence that it suffered partial or complete destruction of its collection as many as four times over 700 years. Maybe the bluebrints for the Antikythera device were burned when Caesar invaded in 48 BC.
"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.
