You like half agreed with me (businesses need commercial support)

No, I didn’t “agree” with you. I said IF a business needs support for their infrastructure/systems they need to pay for that support regardless who provides that support (Microsoft, Redhat, Canonical, SUSE). If support is not paid for, then Windows becomes supported to the same degree as a Linux distro like Arch, which means “community support”.

I do need some citations

https://2-data.com/a-search-for-digital-sovereignty-eu-governments-shift-from-microsoft-to-linux-libreoffice/

France, Germany, Netherlands. Just to name a few.

I’m reminded of Hamburg’s attempt in 2003 to switch to Linux, which they gave up on after more than a decade because of high costs and user frustration.

You mean Munich? That’s the only story from 2003 that I know of. And that wasn’t a failed attempt. It actually succeeded. One of the often cited stories is that they “switched back”, but that never actually happened. Microsoft made a handshake deal with the city to build a new office in Munich if they switched back to Windows, but a new administration was voted in shortly after and nixed that plan. Then continued the move to Linux.

because of high costs and user frustration

Again, if it’s the Munich story you’re referring to, then what you said is not true. There’s always higher upfront costs when switching systems. You cannot use the transition costs as the prime example of costs. You need to account for the costs over a long period of time.

And users were actually happier with the switch to Linux (in Munich). IT support calls even went down due to the stability benefits of a Linux system.

but accept the reality that every large organization voluntarily chooses Windows for good reasons

They chose Linux Windows because the technology people rarely have a say in business decisions and higher-up execs get fed marketing stuff from Microsoft sales people. Even today I hear all kinds of outlandish nonsense from business execs about Linux and open source. Microsoft has spent billions upon billions in marketing to make anything non-Microsoft seem scary and anti-business. Linux on the other hand has no such marketing.

You’re basically implying that every head of IT department is a moron

No, I’m saying most of them don’t have a choice, don’t care, or frankly don’t know any better. 90% of IT admins go into the field with the same marketing that’s been pushed by Microsoft: “you want to get a good job and good salary? Then you need your Microsoft Server 2xxx certifications!”. I actually have those certs, they’re useless once you learn open source and Linux stuff. Simply because when you learn how to admin Linux you learn how computers work, and that’s common knowledge in the field that Linux admins generally (never always) have a better fundamental understanding of computing systems. Whereas your Microsoft certified power admin mainly learns the high level Microsoft way of doing things.

This isn’t the year 2000, with Linux being some newfangled thing. Everybody knows about Linux.

No, the majority of execs have no clue what it is. They may have heard the word Linux before, and maybe they know it has something to do with their company servers, but that’s about it. Every place I’ve worked at I’ve managed to convince the right people to change company policy about the approved OSes workers can use. And each time the policy was originally “Windows only” because “reasons” that no one could explain.

Let’s look at running Adobe Photoshop on Windows vs. Linux

No, let’s not. Adobe is a garbage company with garbage software. If for some god-awful reason you must use Adobe products, then you install Windows and do your work. For everyone else, they can use the myriad of other, and better, tools that replace each and every one of Adobe’s products.

Microsoft is committed to compatibility and ensure software applications work

That’s not how software development works. At all. Microsoft provides a set of baseline ABIs for software to utilize. It’s up to each software vendor to ensure that their software is updated for each release of Windows. The same as any other OS. If software doesn’t work on a newer version of Windows, or doesn’t work on Linux, then that’s the decision/fault of the software vendor.

On Linux, you’ll need WINE, which introduces a third party required to make Photoshop run.

The funny thing about this statement is the number of assumptions you’ve made. Also, see my previous statement about running Windows if your soul is forsaken and you need to run Adobe software.

So if some Ubuntu security update comes out, and breaks WINE with Photoshop, you’re up shit creek until some random community member fixes it or it happens to get prioritized.

That’s not how WINE works. Additionally if you need something for work then use an alternative available on Linux. For professional graphics and 3D applications many Linux native products exist, and your purchase cones with support.

Also, there are various binary distribution types available on Linux that allow a vendor to package up their software so that it works nearly seamlessly on any Linux distro/version.

That costs money, which is against the initial argument here of Linux being cheaper, and it still doesn’t give you as good of a guarantee as just running Windows would have

This is a strawman argument, and you know it.

How is it a strawman? Ok, let me explain:

You posited a scenario that introduces a high level of complexity and an unofficial install path for software that’s explicitly not supported on Linux. Then you imagine an additional scenario built on the first one where the user/company is running business critical software on that “unstable” software stack, and use that as an example of how a company would lose money as a result.

You may as well have said bicycles are dangerous and cars are safer, because if you ride your bicycle on the freeway you’ll get hit by a car.

That’s a strawman.

Edit: I wrote “Linux” instead of “Windows” in one spot