I believe that restrictions for a person of absolutely any age are very important. We all know what the abuse of sweets, gambling, alcohol, even sports leads to. Everything needs to be in moderation, otherwise over time it leads to problems.
If parents do not limit their children in a reasonable measure, then most likely such children are prone to selfishness, and this will affect not only the future life of the child, but also his environment - primarily his parents.
As a parent, I think that's one of our responsibilities and I believe we cannot just let it slide, or else it will be trouble for us in the future when we are too late to stop it anymore.
Failing to caution kids doubles the stress of child grooming for parents. When a child grows up, and some of his flaws are not corrected, he'll not change to good as an adult. A couple of parents invest time in their kid's adequate home training compared to a decade ago.
The sad behaviors of adults today can be traced back to their parent's inefficiency in-home training. And they suffer more stress for not correcting the child when he was a kid.