In the case of GNU/Linux distributions, it's probably just about how it handles dependencies.
However, in the case of Debian, packages are from the mainframe era (eg Emacs 25 is out, but you still get 23 (which is several years old) when you install with apt-get), which is not an inherent problem of apt but it's Debian's neglect for package updates or something.
In the case of Arch, you get only the bleeding edge, which sometimes causes conflicts because some packages don't yet use the library versions that came out next week.
In the case of Gentoo, you don't get binaries, so you have to compile everything. X took about 6 hours on a -j2. Luckily, they do provide a firefox binary, else your grandchildren would have grandchildren before it finishes compiling.
I particularly like the BSDs because you get both binaries, but also the port system which allows you to compile (while still mantaining dependencies in check). Compiling is often a good thing because you can choose, if you so want, to compile wihtout support for some libraries that you might not need. For example, Emacs25 has support for libwebkitgtk which is horrendous, and if your package manager decides you want webkit in your emacs, then you'd have to compile by hand which would leave the package manager oblivious of your Emacs, which in any clean or update may break things for you.