Cinnamon and KDE, and probably Mate, look quite similar to Windows, with the bottom panel having a "start up" menu at the left, the tasks, the status icons and the clock. The settings manager is arguably simpler than the numerous messy UIs on Windows.

I don't think the UI is the issue. I even think some DEs are better than both Mac and Windows on most topics. I don't like Gnome but it is okay I think, especially on Ubuntu. The rough edges are the issue, and above all, the incompatibility with Office (you might have to interact with people using it) and with the various domain-specific proprietary programs.

Windows also has - different - rough edges (and probably mac but I don't know it enough), but you'll find help online or from a nearby acquaintance.

But if I had to set up a computer for a complete newbie, that would be Linux. In any case I would have to help them, but on Linux there are just less disturbances, less risks, easier for them, the UI is better structured, everything is more predictable and since I'll need to help, I'll have better time with Linux.

My issues with a WM usually comes down to UI scaling. Modern laptops (and desktop monitors) with a 4K display render things too small at 1x scale, and too large at 2x scale. Windows and OS X solve this problem by allowing 1.25x, 1.5x, 1.75x scaling with no blurriness; it's not a simple linear resolution scale. Today on Linux I can only find this on Wayland, so I'm already restricted to certain WMs (like KDE, swaywm, Gnome), and even then it doesn't work right across all apps. And when this topic is brought up [1], it's met with "Well, let's argue about the definition of 'sharpness'." If I was a 4K display user trying Linux for the first time this would affect my perception of Linux on the desktop negatively.

[1] https://gitlab.gnome.org/GNOME/gtk/-/issues/3787

My laptop has a 4k screen. My monitor is a 4k screen. I use Linux in a VM. Extending my laptop screen onto my monitor screws everything up with Linux. Windows is fine. And then KDE and Gnome have different UI scaling logic. It’s a real mess.

Funny thing is the method of using xrandr or nvidia-settings to scale continues to work just fine.

I'm using hidpi scaling on 13" 4K screen with Plasma/X11 just fine - that is, until an external screen that wants a different scaling factor is connected. This is still fine though; the only cases where I attach an external screen are presentations or other fullscreen content where the mismatched scale doesn't matter at all. However, if you want to generally work with multiple screens with various scaling ratios, you need to go Wayland indeed.

Same trouble.

The problem with Linux on the desktop is that all polish, quality and consistency is "soon" and has been for 20 years. No one wants to do the last 20% of the job when you can rewrite the interesting bits again for the 10th time.

Microsoft are the same now.

Under X11 you can use xrandr --scale or with nvidia configured this with its display settings GUI. This option accepts as you specified 1.25 1.5 1.75.

You can also tweak the desired font size to taste

I'm with you on this.