That's exactly how it exists. What you're describing here is reality. If you have a machine running Windows XP and you never change anything, then nothing will change. Software doesn't magically bloat over time, those changes happen with updates that add new features. If you never update things, you'll stay on the same software revision and it will run the same as the day you bought it.

A company I used to work for in 2012 had a Windows 3.11 workstation running some ancient software to support an auxiliary system. Many banks run COBOL on mainframes and haven't changed anything since the 70s.

I'm really confused as to the argument here. If you never update your software and don't expect to browse the Internet, old software works exactly like it did in the past. How do you expect it would change?

The whole issue is that some machines been force-upgraded to windows 10 despite users explicitly (or so they thought) responding multiple times that no, they do not wish to upgrade; and then failing to work correctly because of e.g. driver issues.

This is not acceptable behavior - I can understand automatic upgrades that are fully backwards compatible, e.g. a security patch; but upgrade to windows 10 isn't like that.

Because Microsoft didn't write the drivers for 100% of hardware... and tbh, if a company wants they can pay Microsoft to write those initial drivers, and provided the hardware for testing, iirc, they tend to maintain those drivers between versions. There are plenty of drivers that are written by MS, it's pretty common with Printers iirc, and works pretty damned well.

Because foo pro-audio, or bar cnc-board didn't want to update their drivers, or for that matter, more often than not, had a weird installer that simply didn't follow proper practices, doesn't work in the new version of Windows isn't MS' fault.

Nevertheless, because the chance of something like that happening is clearly higher than 0.0000000001%, Microsoft should simply never do such a drastic upgrade automatically. (So, even within Windows 10, they should not automate all upgrades, because occasionally they will have to include bigger changes.)

Also, users will not understand this, and will, rightly, blame Microsoft.

Any trivial update has a higher than 0.0000000001% chance of failure... if you need that level of specificity, you should disable updates, and network connectivity altogether.