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.
But that claim is simply not true. The by far most popular application I have access to right now is Microsoft Word 2007 for Windows and just to verify that I'm not being delusional I tried opening it, created a few documents, then closed all the documents and, lo and behold, that didn't quit the application. To me this is perfectly normal and reasonable behaviour, and considering the incredible popularity of Microsoft Word this must be well-known behaviour to loads of other people too.
For comparison, LibreOffice Writer for Linux also behaves in exactly the same way, closing all documents doesn't quit that application either. (But as the Linux world is notorius for not standardizing anything, closing the last tab of Google Chrome for Linux does quit the application, which I myself find utterly annoying, as it requires always opening a new blank tab before closing the last tab for the application not to quit. Google Chrome for macOS thankfully doesn't do that.)
Only certain programs do this though. On Linux, Libre Office does indeed work like on other platforms, but these types of applications are rare on Windows and Linux, IME. Other applications close when the last document closes, like PDF reader, image viewer, video player, etc. Just because a few act like on Mac because it makes sense for their use case doesn't mean it's the common paradigm.