these spam emoticons create a tube atmosphere of a twitch chat, in which you can immerse yourself, forget about problems and flog, by the way, these emoticons are not entirely incomprehensible, it just takes time to pass them
Because it's fun! In general, it seems to me, there is a reason - to troll your favorite / hated streamer and his style / manner of play.
What couch warrior in a twitch chat will refuse to subtly puff from a streamer. If the streamer is mistaken, there was some funny moment or anything funny in the game - such favorite emoticons as KappaPride, Keepo, Kappa, FailFish, Kreygasm, SwiftRage fly into the chat at the speed of light.
P.S. I propose to arrange a flash mob! In the comment under this answer, write your favorite emoji on Twitch and the channel where you use it most often. My favorite emoticon is DatSheffy and the channel where I often use it is cheatbanned.