OK maybe what I meant was a packaging format and not a package manager, above there was a user that mentioned that all distros have their quirks and kinks, if GNU created a package manager that worked perfectly at first time maybe it’s adoption would go across the distros but as u said to make it perfect the first time is something hard and even harder on early days where nothing was set on stone and there would be always the odd one that would make their package manager.
But if we all agreed early on, one one packaging format (which of course would have to go through many iterations to reach a stable state ) all package format wars would be over and in well implemented ecosystem of package managers of each distro, it would be also an somewhat interoperable one.