Gremlins was actually a huge part of the reason for the PG-13 rating, alongside Indiana Jones and the Temple of Doom. The G rating was starting to gain a stigma for childishness so kids' movies would throw in a damn or hell to get a PG rating, and movies that almost but didn't quite cross the threshold for R landed in PG alongside them. This added up to parents thinking "hey it's PG, so it's family-friendly", and ended up with traumatized kids.