That's not true at all. There are plenty of cheery vaporwave songs mentioned in the article itself: saint pepsi [1], macross 82-99 [2] etc. all early vaporwave entries based on city-pop which is as cheery as you can get!
In fact that's probably the most popular remaining evolutions of the genre, both of the mentioned artists are still huge! (multi-million listens on spotify)
Saint Pepsi and Macross are generally classified as Future Funk artists rather than "pure" vaporwave in the vein of Macintosh Plus. For anyone who is interested in Future Funk (i.e. "cheery" vaporwave) a now-archived and inactive youtube channel by the name of Artzie Music [1] collected classics of the FF genre and is, for now, still available to peruse. The best ones in my opinion were uploaded between 2017 and 2018.
