1. It's for pre-built binary, different OS/Arch need different binary file. So nami needs to know download which file for user's OS.

2. Yes, people are free to create brew taps. But you know humans are divided into 'I will do this' and 'I wont do this'

3. There are there roles: [software developer], [package maintainer], [user].

3. Most cases, [the software developer] is not the [package maintainer]. The software developer only push code, test code , build code. Like we know, build binary is a step of the software developer, but they don't like to create much more packages with apt-get/brew/pacman/etc, so many packages in the centralized PM are outdate. Examples are endless.

4. [User] is people who using software, they like less concepts thing. They just a user, not developer, not maintainer.