Why is it that one needs to bury the dishes to make them kosher again?

I recently visited my grandmother (who’s nearly 90 and not in the greatest health), and she told me many things about the family I never knew before. One thing she told me had me very confused and I was hoping you could shed some light on it for me. My grandmother shocked me by telling me that her and my Grandpa kept kosher the first years of their marriage until the kids were young. Then, one day when they were away on vacation, upon returning they realized that the maid had mixed up the meat and milk dishes. My grandmother wasn’t about to dig a hole in the back yard to bury the dishes to make them kosher again, so she decided on the spot that they were done with kosher. Our family, although proudly Jewish, has had nothing to do with kosher, or nearly any other observance for that matter, ever since. That decision obviously had a major impact on the future of her family for generations to come, and it was all based on the need to bury the dishes. Why is it that one needs to bury the dishes to make them kosher again? Dishes don’t die to need to come back to life or something…the whole thing has been upsetting to me and I need some explanation.