I've seen a lot of people who believe that OwO and UwU are verbalized interjections, and it just struck me that it might be because the ^_^ style of emoticon has gotten so rare that people aren't used to parsing them as faces any more.
@aysamanra Sounds plausible
¯\_(ツ)_/¯
(I mean, I'm a descriptivist: OwO and UwU have also clearly become verbalized interjections. But AFAIK they originated as non-pronounced faces.)