When I read the title I had to remind myself what an uninstaller even is. It's been a while since I touched something like that.

I think package managers are the single most impressive feature Linux distros have over Windows. Everything else I use has some kind of equivalent; for a dev environment you can sort of get by with MinGW and MSYS. But if there's anything on Windows remotely as capable as apt or pacman, I haven't heard of it.

And who uninstalls or updates the package manager?

The upshot of a gated garden is that it is walled and gated. The downside is that it is walled and gated.

And package manager provides hooks to run custom logic when uninstalling. Your arbitrary constraints doesn't solve the problem. Also system wide package manager almost never have the option to install easily multiple time the software.

Software shouldnt update itself? What? Thats crazy

If browsers werent updating itself we would have huge security mess