Why Sketchbooks are the Greatest Thing Ever

I've begun to develop a fascination with documentation.
I've thought of a future in which I keep weekly journals that document my children's lives, and recreate pictures each year to show how they grow. 
Sketchbooks do this with art. 

If the pages are used in a chronological order, these books document growth as an artist.
Looking back at sketches I made in the third grade, I can see the creativity, but moreso I can see how I've improved. The ability to know "I can make this so much better now" is incredible. 
Sketchbooks may not be as convenient as a digital flashdrive or a physical folder from which you can rearrange and display the art. That does not prevent them from still being amazing in their own rights. The fact that you can hold a sketchbook and know years of your life were spent throughout it is wondrous. 
Sure, canvasses and cardboard will always be great mediums, but the simplicity and perfection of sketchbooks will keep me buying them for years to come.