It can't do the literal entire thing an operating system is supposed to do: manage applications and their resulting windows, in a sensible way.
I want to know what application is running.
Sure it's in the dock!
I want to find a specific application window.
Go fuck yourself right to hell.
Wait, the taskbar doesn't show the running windows, like it does on every other OS? It's at least discrete right?
It discretely takes up 1.5cm of the bottom of the screen at all times. It's so discrete it doesn't even need to use the corners.
Uh, alright, well that's all the system space you need right?
Yeah of course just that bottom inch or so .... And a top of screen system level menu bar to display what windows does in the bottom corners.
/sigh/ ok, fine, I just want to be able to full screen a window and still see what else is open.
Burn in hell and die.
I want to be able to easily switch left and right between open windows.
Go full screen or I will shoot you.
I want to move an open window into the other monitor.
You can't because you're full screen dumbass.
I want to let a window present a popup like they normally do.
You can't because youre full screen dumbass. Why would you be full screen?
I want an application like Slack to be able to popup and remove notifications when is appropriate.
Choose to have every single notification persists on screen until you manually remove it, or miss all your notifications.
Can't we trouble you for something in between, where we trust an application and let it manage them in a way that makes sense based on their context?
You can trouble me for something in between these cheeks, shit stain.
Like honestly, I fucking hate what an advertising and AI filled mess Windows is, but it can actually manage your windows and virtual desktops in a way that makes a modicum of sense.
It feels like a single Apple product manager decided that the way that they use their computer (a single application at a time, no windows to manage) is the only way anyone does, so who cares if we implement a nonsensical full screen paradigm, it makes one tiny niche edge case slightly simpler.
Concerning your window management troubles, have you tried Exposé/Mission Control at all? "Ctrl + Arrow Key Up/Down" will show all open windows, and all open windows from the currently used application respectively. On trackpads this is bound to a four finger swipe up/down.
To cycle between the active application's windows use "cmd + >" (add shift to cycle backwards), or alternatively you could right click an application's dock icon to view a list of all its open windows.
Yes, I use this all the time out of necessity but it's still hogwash.
Mission Control is ok for selecting windows on a a single desktop as long as you have less then 6 open, it starts falling apart after that, and for some reason, no matter what, it makes the icons for full screen apps so small it's impossible to tell which particular mostly white web page is which.
Ctrl + Arrow Key - switches between only true Full Screen applications, forcing you to use Full Screen, instead of just maximizing. Want to know which windows are coming up next in the list? Too bad, use mission control.
CMD + tab - switches between your last used applications, it does not switch between windows.
On Windows:
you have a taskbar at the bottom where all running windows are neatly tucked away under each application, each with a preview.
With Alt + Tab you go through a list of last used windows, not applications. With a three finger swipe left or right, you can switch between them with a single gesture. You can configure this list to be all windows, or just the ones on that monitor. Their previews are always a predictable and visible size.
you have virtual desktops where you can put your entire window arrangement across multiple monitors away, and start a completely fresh workspace for a different task.
I don't use full screen windows much because I do agree that they become kinda annoying to find if you have more than 1-2 open at a time, mainly because I do most navigation with Exposé and they don't nicely integrate there.
You pointed out that "cmd+tab" doesn't cycle between windows, but that's why I recommended "cmd + >" in my first comment, since that's exactly what that does.
"Ctrl + Arrow Down" will only show your currently focused application's windows, it's different from "Ctrl + Arrow Up" which shows every application's windows. So if you just use "cmd+tab" to focus on whichever application you're currently looking for, and then hit "cmd + >" a few times (or "ctrl + arrow down") you should find your window pretty quickly. Just a different process than cycling through every window on Windows, but I wouldn't call it worse.
Unless you have like 20 windows open for a single application, I guess I could see how things could get convoluted in that case.