Parents who have been struggling with sleeping problems for a while usual have tried sleep training methods and have failed. This has lead them to believe that all sleep training methods are bad or produce a lot of crying or just don't work.
In my experience, when I investigate how parents handle sleep training, they are usually not implementing the correct methods. When correctly applied, sleep training methods work and can be done with minimal crying or fussing.
Sleep training is not about punishing the child or making them cry. The purpose of sleep training is to help the child get better rest and do it with the least amount of crying possible.