> When system package managers get properly documented maybe
Invalid complaint. The major package managers are extremely well documented. Even some of the minor ones, like archlinux.
I don't think I'd call pacman minor anymore, it's pretty well known and is the package manager for msys2. slackware, on the other hand...
When system package managers get properly documented maybe ... when instead of having 1 package manager per system , we have a single package manager for every system ... otherwise no, use the package manager that comes with the language if there is one.