That thing of no software updates is very weird.
Windows 7 is many years old yet I can still use the latest version of Firefox.
Yes, but you can't run the latest Chrome on the Windows XP. And you can't run it on Pentium 3 (because it doesn't support the latest SSE4).
Modern software needs a modern OS and modern hardware.
Microsoft has much more resources than Debian team, so they can provide support much longer than Debian.
This is because of money Microsoft gets for their products. But Debian is free. Maintainers are volunteers. They simply do not have enough time to spend it on backporting software to the ten years old distro..
Sometimes software can't run on modern Windows, and Microsoft creates shims for it (you can google for that term).
So, they have hacks saying "if this app is called [some_app_name], change API behaviour to support it".
Linux kernel ABI is backward compatible ("We do not break the user land" (c) Linus Torvalds): that means old software should run on the latest kernel, but not vice versa.
But software also depends on libraries, and libraries are not always backward compatible.
The Debian team guarantees that software installed with package manager (apt and friends) should run fine.
You can try to download the latest Firefox and run it on Debian 8, but there are no guarantees for it to work.
Debian has thing called LTS:
People who really need long LTS use commercial distros like Redhat. But IMHO it doesn't make any sense to use it unless you run a business that depends on it.
For desktop I recommend to use the "stable" version of Debian and upgrade it every several years.
(I now run bullseye which is the "testing" version, but it will become stable in the next month or so: not a bleeding edge, but pretty modern and stable at the same time)
Isn't there a way to update user programs without updating
the operating system itself.
Classic UNIX and Linux approach is to install everything via package managers and use the latest version available in package manager for the certain OS version.
There are modern ways to install software along with all its dependencies much like Windows people do.
Canonical (the company that runs Ubuntu) provides so-called "snaps".
There is also "docker": a tool that downloads all dependencies and only depends on your kernel.
But again: the latest version of Firefox MAY need something that the ancient kernel simply doesn't provide.
The safest way to use Debian is to:
* Run "stable" version on Debian
* Upgrade it to the next "stable" once Debian team releases it
* Install everything from the package manager.
It could happen that you wouldn't be able to install the latest version of software released last week, but on the other hand you will be sure that this software was tested and it is stable and compatible with everything else in your system and there are a lot of people who run the same version of this software (along with all other libraries and the kernel) on their production servers, so everything is rock-solid.