Before discussing which one is the best approach, let’s define our terms.
Libertarianism is a political ethics, that means it’s a set of rules of what the law should be. Libertarians believe that one is wrong in initiating aggression against another individual according to the property law.
What about thick and thin libertarianism? There’s a debate in the libertarian community on what libertarianism should compound.
Thick libertarians argue that the political ethic theory isn’t enough. According to them, we should include other values into the theory. Some will believe that libertarians should publicly work against racism, be feminists and fight for social justice. Other thick libertarians will defend traditionalism, family structures, and Christian religion as fundamental components of libertarianism.
The argument behind the tick libertarian’s view is that a political theory isn’t enough to convince the common people. We should use more profound values that people can identify.
The thin libertarian rejects that approach. He understands that as individuals we all believe in different things like religion or anti-racism. However, the law shouldn’t be responsible for enforcing those values. Thus, a libertarian will have his own values, but when he is arguing for libertarianism, he's promoting the political ethics and not his other values.
Moreover, integrating those values into the libertarianism can divide the movement and make the ideas repulsive to many people. It's rare to find individuals that are profoundly authoritarian, but it's easy to find people that identify with the left or right values. If we shift libertarianism to either of those paradigms, it'll be difficult to attract the other side. Organisations like Students for Liberty, Praxis or FEE can still hold other values than the political theory to attract new members and convince the people. Individuals are more motivated to work with people that they share values, it's true, but those values can be at an organization level, instead of a movement one.
One last thing, libertarians acknowledge how ignorant we are to determine people’s needs. Central planning is impossible. From this proposition, how can we be certain what's the best social structure for society? Like goods and services, let's let the people decide for themselves what's best for them.