Sooo, i dont have a system package manager to use to add more packages, not without building my own image ontop of Bluefin/Bazzite.
Also, all the packages on Brew are fairly well tested, while mostly on OSX, they officially release Linux prebuilts for Linux and get tested equally. Brew has been around for ages.
And I havent used MacOS for 8-9 years, and only for a small stint. Not long enough for it to do things.
Also per official stats: https://formulae.brew.sh/analytics/os-version/90d/ Ubuntu makes up ~20% of brew usage, and the Universal Blue family is about 2% and growing.
There is absolutely a usecase for it and its just as good if not better, as most tools are more likely to be statically built, and you donthave a giant dependency mess and other nonsense to deal with. Its cleaner.
On an immutable distro, its a lot of Flatpak, AppImage, and Brew/Mise/etc. Layering packages is greatly discouraged and as the ecosystem moves towards Bootc images over OSTREE ones, the option will go away entirely. You either build a custom image with yoru custom stuff layered on yourself (there are templates and Github CI stuff to help with it.) or you use other package managers.
Also another win is weith Brew, i can reproduced my tools and environment quickly and dont have to deal with Distro quirks. Brew works the same on almost every distro, same pathings, same behavior, and even offers the Brewfiles to let me specify my setup.
I recently switched jobs and had my work setup installed and created within mins of booting into a fresh install and I was working shortly after.