It would be a mistake to view legitimate critisms of greed as favouring socialism or marxism and disfavouring capitalism. Even Adam Smith had moral principles which were opposed to avaricious laissez-faire attitudes held or criticized by modern peoples.
There are adherents of capitalism who do not follow the Church’s teaching on charity and stewardship, as well as treating your fellow man with dignity. Notice that the artice talks about the “purely economic conception of man” which is a problem in both modern capitalist and communist philosophies.
None of this requires legislation from the state, if it did, then the point of it would be lost - it is supposed to be an act of brotherly love not of compulsion.
In school, we had a class called, “Peace, Justice and Liberation.” We discussed and studied many of the works dealing with mentioned. In particular, we looked at liberation theology which is common throughout South and Central America.
http://www.vatican.va/holy_father/john_xxiii/encyclicals/documents/hf_j-xxiii_enc_15051961_mater_en.html
Pacem in Terris by John XXIII
Quadragesimo Anno by Pius XI
Quod Apostolici Muneris, Humanum Genus, and Libertas by Leo XIII
All these are good to study in conjunction with Rerum Novarum.