This is true of macOS as well now. You can defer it, but you're nagged pretty consistently. There was a time I remember when installing updates on OS X didn't require a reboot unless it an os update. Now, so many things are tied together.

This doesn't require a system reboot, but if you're updating Xcode, you can't if iTunes is open. I understand shared libs and things, but I don't really see that much difference anymore between rebooting for Windows updates and macOS updates. YMMV I guess.