This is a joke based on people ending sentences with sequences of w's like "wwwwww" online in Japanese with a meaning similar to "LOL" in English. This is originally from "w" as an abbreviation from "warai" meaning "smile/laugh."
People now refer to it as "kusa" meaning grass, becaus it kind of looks like that.
Because it's sometimes fun to mess around with esoteric coding languages?
I mean, there is a programming language based purely around whitespace sfter all...