This article claims that Hyperscript is "Something you could just type out from memory, without referencing anything". I don't understand this assertion at all

This article claims that Hyperscript is "Something you could just type out from memory, without referencing anything". I don't understand this assertion at all. There is a grammar that must be learned, and it is different from existing solutions, which means most humans will need to reference something until they become familiar enough to work without documentation. I don't see how this is different than React, vanilla JS, or others. The benefits of this do not shine through for me.