You don’t need the distro to package your sodtware through their package management systems though. Apt and dnf repositories are extensible, anyone can publish. If you go to copr or ppa you can have a little extra help too, without distro maintainers.
The headache comes up when multiple third party repositories start conflicting with each other when you add enough of them, despite they’re best efforts. This scenario starts needing flatpack, which can, for example concurrently provide multiple distinct library versions installed that traditionally would conflict with each other. This doesn’t mean application has to bundle the dependency, that dependency can still be external to the package and independently updated, it just means conflicts can be gracefully handled.