It's okay, you don't have to 'get' it.
Some people enjoy making them and making others smile. It's actually not a difficult concept to understand though.
Before I had the stroke, I used to knit and crochet, but far far far too slowly to make these. I'm not terribly fond of the one you have linked to, but there are some amazing ones and if I had put that much time and effort into knitting or crocheting them, they would be going inside someone's home to be looked after carefully or played with not put outside in all weathers!!
However, some people knit or crochet much more quickly and get real pleasure out of displaying their projects around the local community making other people smile and I am grateful to them.