The plausibility of liberalism at least in part comes from the truth that we really do need a certain degree of freedom to achieve the good life. Part of raising a child is gradually giving him more freedom to choose the good. However, part of this raising is teaching him precisely to choose the good, rather than not. Each step of new responsibility presupposes the established habit of choosing easier and lesser good so that he will really want to higher goods rather than being compelled to them. This however is only to be free to choose the good that we may be tightly bound by it, that is to form the interior habit or disposition of choosing the good.
The implausibility of liberalism comes with the massive difficulty that liberals put on men to live the good life. Every vice is available and in mass quantities without punishment or discouragement. Even a virtuous man dedicated to the good life would struggle and even worse for children raised in such an environment.
Moreover, men in general are not virtuous and the freedom that liberalism proposes will destroy them through intemperance, imprudence and every vice. No matter how good it would be for them to choose it for themselves, most men will ruin themselves and others in a liberal society, as we can see.
A good society is one where we are bound to the good by real concrete practices and traditions. A society that disparages these or in reality encourages every evil practices is a bad place to be.
Edward Feser: http://www.edwardfeser.com/unpublishedpapers/socialjustice.html