Until I read the parent article I hadn't realised why I have been so lazy about installing linux on my current laptop, which came with win 10. It's the desktop manager.
Winkey + left/right arrow key snaps the currently focused window at the corresponding half of the screen. Then the desktop icons appear on the other half and you can move around with the keys and press enter on one, and it snaps on the other half. Then press Winkey + up/down key and the focused window snaps to the upper/lower quarter of the screen and you can again choose another window to fill the remaining space. Winkey + Ctrl + left/right arrow changes desktops. With Winkey + tab you see a desktop overlay and can send windows to other desktops from their context menu.
And all without every having to touch the mouse. I had Xmonad on a previous laptop and it's just like that, except for all the arcane configuration files. It works out of the box.
I mean, it's still windows 10, right? I plug it back into my dock and it LBSODs (it's Light Blue now). Every other week I go into nerd warp spasm because of some inane stupidity, like, my machine keeps going to sleep if I leave it idle for a couple of minutes after I woke it up over bluetooth and that's not configurable. Or it randomly adds a new language to my language bar. Stuff like that. It's windows.
But the desktop manager is actually, very damn good.
What you're describing does exist, but as with most things GNU/Linux it's not user friendly in the slightest. What you need to do is to set your Xft DPI to a level that is comfortable for your HDPI monitor, then you need to 'upscale' your second non-HDPI by an equivalent amount. For example I have a 28" 4k monitor, and a 24" 1080p monitor, and I typically prefer a scaling factor of about 150%, so in my .Xresources I have 'Xft.dpi: 144' and I need to upscale the 1080p monitor with the following command:
xrandr --output DisplayPort-0 --auto --pos 0x0 --primary --output HDMI-A-0 --auto --pos 3840x540 --scale 1.5x1.5
Where HDMI-A-0 is the 1080p monitor. I've had a bug in the past where I would need to use the --panning option (e.g., --panning 2880x1620+3840+540) with the correct geometry to get everything working, but it seems to work fine now without that. If you do need to mess with the --panning option though may god help you.
Most terminals have a feature to copy selected text into clipboard automatically, even xterm. This doesn't have much to do with tiling WMs.
With vim , you may need to set clipboard. I personally use neovim so everything just worked out of the box.
Windows 10 snapping keyboard keys are top tier. Not automated tiling, but save so much time. Also the GUI is beautiful on whatever screen you plug it into (including 4k). On Linux DE's right now? Mint or gnome will show options to scale up 200%, 300%, 400%(!) Even 200% is far to much.
Tiling WM+HDPI doesn't quite exist. Most use gtkrc, xresources, and the WM config to play with sizes. But that doesn't translate across different monitors. So it's a flawed system.
Let's assume HDPI+linux and tiling WM's were ironed out: In practice tiling WM's aren't as good because once you get into a terminal window, it's not as easy as it looks to copy from terminals <-> "gui" applications. It's possible, but the time spent ironing it out may not be worth the trade off for some. For instance I can't rely on copying from a vim inside of tmux, I do :!leafpad % to open a file and copy from that.
As for HDPI and tiling WM's, swaywm is an i3 for wayland that appears to support it: https://swaywm.org/
If you're okay with just HDPI and basic snapping: https://system76.com/pop or gnome 3.32 (that'd be ubuntu 19.04 or debian experimental at the moment I believe). Gnome 3.32 has fractional scaling. That'll scale by 125%, 150%, 175% (probably what you want)
Gnome's snapping isn't a smooth as Window 10's. Windows 10 is really good and half-sizing vertically. IMO: It'd be ideal if gnome 3 behaved the same as windows snap did by default. Extensions can help, but if you rely on them, they're limited and often behind of the latest gnome version (or two or three, or become abandoned entirely [1]), and don't wire-in to keybindings as well.
[1] https://extensions.gnome.org/extension/723/pixel-saver/