I use portrait monitors, too. Great for web development. You can see an entire web page you're working on in a single glance. No scrolling!

It's helps with coding, too, but scrolling is still usually necessary there.

macOS is fairly weak, being more inclined to manually accomplishing it.

MacOS is good for doing it horizontally, but you're right — there should be a mechanism for vertical tiling on portrait displays in macOS.