I see a few issues. First a free market for jobs is good if there are correct market incentives. While i believe that they do exist in a free society, they do not exist currently. The entry barrier to work self-employed is high and often exclusive to social benefits. In addition we have strong social stigmatisation of the unemployed. This creates a situation where the demand for low end jobs is very high, resulting in bad pay and a system where most of the profit ends in the hands of the employer. A UBI could help to generate a better market equilibrium. It also is the freest form of social benefits possible. Therefore I advocate for a UBI to replace all other social services inside our current system. What happens when we exist the current corrupt system is of course a different question.