I have a thesis that I want to test - soap bars and bottle caps

I think I have stumbled upon something similar to the pencil and cassette tape, that will divide the xennials.

I was in a soap shop and I saw that they had these wall mounted prongs where the soap bar spins. The switch the soap, you remove a nut at the end. I remarked to my wife that you don’t really see these anymore.

I then said that our kids will never figure out what you were supposed to do with a soap bar and a bottle cap. She looked at me like I had two heads and had no idea what I meant.

She is a younger xennial, I am a middle xennial.

So fellow xennials, have I found something that divides our generation? Do you know why soap bars and bottle caps go together?