Old style razor blades for DE safety razors are also still sold, and standard. People have their brand of choice based on shave qualify, but the blade holder will accept any of them.

It’s an interesting glimpse into the future of batteries, because there are exactly the same incentives involved with batteries and modern razors:

The GGP poster has never in their life ever seen the traditional interchangeable standard double blades and razor, can’t even conceive that it was and is an option.

Many people in the future will never in their life ever see interchangeable AA/AAA/C/D cells, and won’t be able to conceive it was and is an option.