Maybe the "atomic CSS" part wasn't very clear—we just meant the concept of atomic CSS.
We love tailwind as everyone else in their right mind, but we're using our own flavor of the concept I started years ago: https://fractures.dev
On the why: We plan on having a lot of novel, one off interfaces, which TW isn't just right for. CSS is. We also don't have an frontend scaling problem, as I'm the sole developer here.