The appeal is to the creators, resulting from the differences in unit economics for monetisation structures related to youtube shorts, tiktok, reels, snapchat etc., vs. conventional youtube, facebook or instagram videos.

And also there's appeal to Youtube as a platform, being a place logically suited to this new paradigm of shorter vertical videos where discovery is mostly algorithmically driven but having some issues with the organisational structure of their content that make it uncompetitive with platforms which popularised the format.

It's not appealing to Youtube users because a choice to use Youtube has historically always included a deference to the conventional youtube video format. People that prefer tiktok format would organically become tiktok users not because tiktok is a better platform than Shorts for it, but because youtube already existed and established its own format, so it's not the logical place to go for something that isn't that.