Simplicity is the opinion of each computer user.
For VE3WI, the software he uses runs under windows. So he uses windows for simplicity.
For K7MEM, the simple solution is to just buy new hardware when microsoft obsoletes any of his working hardware. (And that's exactly what microsoft is trying to get its users to do!)
AC7CW just doesn't think Mac or Linux is a good choice.
We're all entitled to our opinions, and each of has our own needs. Nothing at all wrong with that.
As for me, I buy new hardware only when absolutely necessary. I'm retired and on Social Security. I can't afford to replace/upgrade computers whenever Micro$oft gets a wild hair where the sun don't shine. I also no longer need Windows for my job, since I no longer have a job.

My newest laptop, other than a couple of Raspberry Pi machines on the workbench, is a 2017 HP Envy that came with Windows 10 and now runs Mint 20.3. It works far better with Mint than it did with Windows, even after I upgraded from 10 to 10 Pro. That was my last version of Windows, and I will never use another one.
I've never used Mac. As a federal employee, I had to use windows. Got very upset when windows 8 came out. Got sick and tired of my choices being taken away from me, got nauseated over all the personal information that they were trying to get from me, and threw away my last windows 7 install disk about two years ago.
crApple may be even worse than Micro$oft. My sig-other was given a Mac almost a decade ago by her crApple-fanboy brother. She hated it and gave it to me. I hate it too, because of the OS, not the box itself. I can't upgrade it because crApple declared that model EOL last year, although the hardware still works perfectly. It's still good for testing different Linux-based OSes under VirtualBox, though.
For me, simplicity is not having to continuously buy software, knowing what my OS is doing, having access to all of my OS and not having to worry about drivers. I do have to be careful about what printer I buy. That's about it.
I tend to stick with HP printers/scanners because they are all supported. I have an old Brother laser printer that I never could get to work under either Linux Mint or MacOS.
For me, simplicity is this: if I can't figure out how to do it with Linux, I just won't do it.
Agreed 100%. Micro$oft jumped the shark when they absolutely failed to develop a usable mobile OS. Android (Linux kernel-based, but not GNU) and crApple absolutely own that market, 50-50. I really believe that some of that fallout has come to hurt Windows as well. They'll have the majority OS (all versions combined) for quite some time, but they now have competition that they just can't deal with.