Letting someone be responsible for, and/or face the repercussions of their actions is, in some cases, entirely necessary. But, like anything, the individual has to decide when and where, and to what degree, the response is appropriate.
Obviously, very young children do require assistance, as one wouldn't let a small boy walk home in dangerously cold weather because he forgot his coat, even after you reminded him. You'd find a way to get his coat to him, and give him an earful when you did so. You could later decide on a small punishment, like taking away a toy or a privileged, because he failed to listen, but you certainly wouldn't risk the child getting frostbite just to prove your point.
But if someone is an addict or alcoholic, and you keep giving them money, guess what? They will take that money and go buy drugs & booze with it. You're enabling their addiction. As hard as it is, you can't cave in. You can offer them a place to stay while they detox, or offer to drive them to rehab, or something similar. If you keep making it easy for them to continue their self-destructive behavior, then it's like giving them permission. My sister was a drug addict and alcoholic for 25 years, and that might not have gone on for so long if my parents didn't keep bailing her out. She stole from them, lied constantly, destroyed their property, neglected and abandoned her child, sent her husband into a nervous breakdown and gave my mom stress-related heart problems. It wasn't until the courts took her child away that she finally stopped.
It's obviously a matter of degrees, the age and maturity of the person involved and the severity of the problem.A child who refuses to do homework pays by spending her summer vacation in summer school or perhaps even gets held back a year. Someone who continually breaks the law, however, will pay by spending some time in jail. That's how life is. You don't help someone by not letting them see the consequences of their actions.