There are no doubt other methods of getting rusty things loose. No question that heat is faster, many times using heat is not an option. Many times soaking for even days or weeks ends up in a better result than the faster more destructive methods. Anything can be taken apart by some means but when it comes time to put things back together is where it makes a difference. So each to their own but it sure helps knowing more than one way to achieve the same thing.
