I don't think it's that crazy. Hyprland has, for a long time, looked really lovely when configured. But most don't want to configure it, the linux ricing community is really small in proportion to even the people who want to install Linux. Omarchy is dead-simple to install, has good documentation, decent opinions[1], and has huge influence because of DHH himself. I stopped running it myself after while, in favor of configuring my own Hyprland install, but it's an easily accessible shiny new thing by someone with a big following. Seems reasonable to me that people like it.

[1]: I don't agree with all of them, e.g. the chatbot shortcuts. But they're trivial to disable and/or redirect and, indeed, the project does a good job of trying not to mess with your changes.