The poor should not have to depend on what the powerful agree to give them in order to prosper. A free market at least offers the possibility that you can prosper no matter how selfish and oppressive the others in your society are. Group politics are founded on the idea that enough votes or pressure will shame or compel your neighbors, or even oppressors, into giving up good things. This works moderately well, but has three enormous limitations:
1. The individual is still powerless. He must give his power to the group, with all the compromise and unwilling association that implies. Whatever the collective decides, he is then bound to in a simple up-or-down vote. In a group large enough to have national impact, he is as voiceless as he is in the nation as a whole. Only if he can penetrate to group leadership does he have a say. Elections and government might have to work this way, but a person’s individual freedom and prosperity should not depend on anything so flimsy.
2. What the group can extract from the whole is necessarily limited, and the distribution must go to the whole group. Group politics can bring the indivdual some security, but it cannot ever provide wealth. It can improve justice, but has little impact on fairness.
3. Group politics are economically inefficient, reducing the overall wealth that a society might have.
I prefer not to stake my happiness on how much I can influence those in power to do nice things for me. It's not that group efforts don't do anything, but that they don't do enough.