Board Thread:General Discussion/@comment-26006155-20190617222636/@comment-26006155-20190706054157

From the conversations of Alphys, Undyne, and Bratty and Catty we learned that the traditional method monsters use to get their technology, is by studying the garbage that falls from the human world.

So until Gaster arrived, the monsters had no other source of technology to draw on. Their tech was all tied to the surface world of the humans.

An important lore clue.