Let's say I'm focused on my terminal, and I want to focus on the Firefox window that's besides me. The shortcut is Alt-tab Alt-~, but after doing the first key:
1. All Firefox windows in the current workspace go to the top of my screen
2. If there were no Firefox windows in the current workspace, OSX helpfully moves to the next one.
3. Even after that happens, I need to cycle among all Firefox windows. There's no way to Alt-tab repeatedly between pairs of windows of different applications.
Once you pick the a window, it will be foregrounded. Everything else will stay the same.
Think about it, if you have N apps open with M windows each, then on macOS you need at most N+M key presses to reach your desired window, while on Windows you may need up to NM key presses.
23 years ago, Windows allowed me to do this in 1 or 2 clicks without looking. Now it's either a lot of clicks and observation or making a mess of my workspace.