I don’t think that’s a very accurate assessment at all. NixOS, VanillaOS, and Bluefin are three of the first atomic distro’s I think of and they’re all heavily aimed at developers. All of them offer features to help separate development environments, which improve reproducibility of packages and environments. I prefer the Nix approach to containers, but each one definitely offers benefits for software development.

I do software development and need a ton of tools installed that aren’t just “flatpaks”.

Every atomic distro supports distrobox and other containerization tools, and many support Nix and brew.

These distros are good for people who want to treat their desktop like a phone, but flatpak kinda lets you do that on any distro. Atomic distros are great for those who want to use tools to separate development environments for purity and tinker with the ability to easily rollback.