Much of its popularity is apparently via certain YouTube influencers in sponsored videos that often hide their sponsorship or affiliation with Omarchy. It's gained quite a following in the "man-o-sphere".
Omarchy was formed as a culture war weapon/counterpoint against other Linux distros with codes of conduct. DHH believes such codes are used by clowns and that prohibiting racism, sexism, homophobia, etc is stupid.
DHH has some interesting views on "gypsies": https://world.hey.com/dhh/wolves-sheep-and-gypsies-ba44af6a
And "retarded" immigration policies: https://world.hey.com/dhh/three-sacred-cows-that-must-die-so...
From a technical perspective, it's been referred to as an opinionated theming layer on top of Arch Linux or a vibe coded dotfiles project as it is mostly Arch Linux with AI code atop.
From a financial perspective, DigitalOcean recently pulled funding for multiple open source projects like GNOME before this $3 million investment in Omarchy.