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When a child asks for X, they are not really asking for X. They are asking for X, and for you to deal with any consequences of that action, regardless of how poorly-executed. When you do X you are also dealing with the consequences, so it's really no concern of theirs.

Mentioning that a parent gets to do X while they do not is just a way for a child to score a point against foolish parents in an argument.

You are right to a degree. Clearly a parent can lose credibility by being too hypocritical. But you shouldn't feel any general obligation to treat children as adults or yourself as a child.