Without intending to be inflammatory, I think that the mindset that you are espousing is broken.

Security is is a real issue for a subset of computing tasks. To further your point, for those tasks you can argue that constant vigilance and patching are a necessity of the modern world (an alternative and arguably better approach would be that formal verification and not updating, as often applied in safety critical control systems.) However, security is often used as a pernicious ruse for forcing obsolesence: want the latest security patches? update to the latest OS version. Oh look, the latest OS version no longer runs on your perfectly good hardware. Or similarly, oh look, your perfectly good software no longer runs on the latest OS version.

But now consider the subset of computing that does not need to involve security either because it has literally no security implications, or because it can be sandboxed by the OS (e.g. games, music and video production, architectural design, scientific simulation, mathematical research, ...) There is a large body of this kind of software that works perfectly well for any number of years (modulo forced obsolesce initiatives like "modernising" the UI or moving to the cloud). I would argue that the primary function of the OS should be to provide a stable platform for running such software securely. Yes, the user could learn how run it under emulation, in a container or VM, but then what is the purpose of the OS?

The alternative is a high software maintenance burden/cost to everyone (for applications to just keep the lights on, or users to stay current in a churning software landscape) and/or the destruction of a massive amount value in developed but no longer easily able to be run software: this value destruction here is twofold: (1) the licensee can no longer run the software that they pay for, and (2) the effort expended to develop said software is discarded.

Okay, I understand what you are trying to say, but some of what you are using as examples doesn't support your argument. Games, unless they are simple single player games, need the network. Scientific sims and math research are best served on the latest hardware, which often needs the latest OS/software to get the most out of it. I think your arguing that MOST software should run without needing to be updated, and when we lived in a dial-up world and before, that was a very viable position. But with all of our machines on an always on network, the OS has to be kept up to date.

Most businesses just want things to work; their software/hardware costs are often rounding errors when amortized over their lifetime. I'm sympathetic to users who have paid for programs wanting to run them forever, but software businesses have to make money and sell new versions, so they add new features and follow the OS upgrades. It's hard for businesses to support older software or a big diversity of versions; it's why companies mandate a standard and try to enforce it.

With Microsoft, they are making millions on OS and related basic programs, and so can afford to support things for a long time. With OSS like Linux, there is less funding and less people who are interested in running old versions. As someone who has had to keep some software up to date on Linux, it can sometimes be more of a pain to update a package (because of dependencies) them to just recompile the thing from source. The 5 years that LTS releases get are good for 2 average commercial update cycles, which I think is reasonable. Beyond that, people's skills are going to be out of date.

Because you might want to run more than one program at a time without having to spin up a VM to do it.

I run many programs at the same time AND run VMs; as long as you have enough memory, this shouldn't be an issue.