Debian is a well known but seldom used Linux distributions. Especially newbies in the Open Source community are preferring alternative Linux distributions like Fedora, Arch Linux, Ubuntu and Suse. To understand the mismatch better why Debian on the one side is great but is seldom used it makes sense to analyze the distribution from a beginner's perspective.
Suppose a computer user has logged into a preinstalled Debian in a computer room at the university or has installed the system in a virtual environment on his home PC. After entering the command “uname -a” the user will notice that not the recent kernel version from kernel.org was installed but only a longterm kernel. The same picture is there after testing out the python3 interpreter. It will shown in the interactive mode that the installed python version is around 1.5 years old and was compiled with the previous GCC Compiler. Even if the user won't need the current software version the impression is, that the system is outdated. In the next step the user will try to playback perhaps a video in the H.265 format which is running fine in Windows and MacOS but in Linux there are some codecs missing.
In summary, the user will come to the conclusion that the distribution is working with outdated software and in addition is not very powerful. So the chance is high that the newbie will deinstall the system and prefer a different operating system. Which is maybe a Linux system but in a different distribution.
It is hard or even impossible to explain to the user why most of software is outdated and at the same time it is the most recent version available. Even if the explanation contains a detail description about the advantage of stable release management and the hint that that the software is working bugfree, the newbie won't agree to the Debian advocacy.
But let us try to take the challenge more serious and explain in a single version why Debian is using outdated software. Suppose, the software installed on the harddrive is never older than 1 week. The logicial consequence is, that the system maintainer has to run a complete reinstall of the software every week. That means, every sunday evening the local adminstrator has to run the update script which will download around 3 GB of new and fresh sourcecode from the internet, is processing all the updates for around 3k packages and then a short function test is made. The overall procedure will take even with a quadcore cpu and a fst internet connection many hours and requires manual intervention. Nobody likes to do so. And that is the reason why Debian is updated only every 2 years in such a way.
It is not possible to deliver an to date Linux distribution which doesn't need to be updated. It is a contradiction and only one objective can be realized. Either somebody can simply work with the system or the user has to manual update the system every week which includes the chance of a reboot failure.
The advantage of Debian over other Linux distribution is especially visible in larger computer rooms which have 30 and more workstations and it obvious for a server system. In both cases the admin of the computer is not motivated to run every week an entire update which includes to download gigabyte of .iso files from the internet and install the packages over the older versions. Such a complicated update should be run only once a year if nobody is using the machines.