They certainly can clean everything after them. And I'm pretty sure that many of them do. When macOS user drags application folder to the Bin, application does not have a chance to clean after itself.

Just because some Windows uninstaller are bad doesn't mean that all of them are bad, or that uninstaller concept is bad.

Now I'd welcome for operating system to be built in a way to let user to delete everything related to the application. Maybe android or ios are built this way, but not macos.