It explains why induction from empirical observation can't tell us whether or not the universe was caused. Note that over those two million years, no-one has ever observed any universe-beginning, or any beginning at all for which there was no prior time. So we have no observational basis for insisting that the universe must have a cause. Note further that among those observations are those of quantum events for which we have not observed any prior sufficient cause, and also that every observation for which we've observed a cause is, from an inductive perspective, equally good grounds for inferring that every effect must have a prior physical cause located in time. No-one has made any verified observation of causation-by-deity, causation-from-the-immaterial, causation-without-time, or causation-from-a-different-time-dimension. So as far as observation is concerned, none of these are any better off or better supported than an uncaused universe.