Those tools do work. And when they fail they fail because the problem is not what you think it is. At any rate manually copy and pasting files is a waste of time with modern OS's. The objective over the years is to make OS's safer, more secure and reliable, not the other way around. Making it easy to copy and paste system level files does just the opposite. So they all have a variety of systems in place to make this very difficult if not impossible.
Apple implemented
System Integrity Protection with 10.11 almost 3 years ago. Linux has
Security Enhanced Linux which was introduced some 20 years ago. I'm sure Micro$oft is doing work on similar tools.