But that is Debian.
Debian is purposefully a conservative distribution for people who value stability over novelty.
This doesn't apply to faster-moving distros like Ubuntu, nor to rolling release distros like Arch.
And in fact, a common thing on Ubuntu is to have separate PPAs for packages that are not maintained by Canonical. Often, there's even an (older) version of some package in the official repositories and a PPA with more frequent updates. Similiary, Arch users have the official repositories as well as the AUR.
I think this is false. Linux users typically don't like "one-click downloads". Ideally, everything they install is installed through a package manager, so they can always keep track of all the software they have on their system, although for some shell utilities like the version managers mentioned below, install scripts also seem to work (the key point is that it's trivial to uninstall these by deleting a certain folder; for arbitrary software, this is much harder and hence why a package manager is preferred).
If you need a runtime for some program, I think many people are usually comfortable with using an install from the official repositories or from a PPA. Now, developers for the specific language will usually want to have some more control over the different versions of a language, so they might use tools like rbenv, pyenv, etc.