Marx studied philosophy- especially Hegelianism like so many others in his era (as well as law) before setting out on his life’s work. Primarily Marx contributed to sociological analysis at which he was quite good, and not so much so at metaphysics or designing an ideal economic system.
German idealism of the 19th century had influences from Hegel and romantics that discounted ordinary social structures and instead felt themselves a little above the worldview and rote, somnolent lives of the masses of society. Nietzsche was one of those, yet so were so many others, and they were influenced by Darwinism, prominent atheists (i.e. Feurbach) and anarchists (i.e. Kropotkin). Marx was a Jewish intellectual and Jews of 19th century Europe had been victimized by pogroms and so forth going all the way back to the destruction of the temple in Jerusalem in 70 a.d. when a million were killed and the remainder scattered in exile (diaspora), hence Jews sough a Jewish homeland- so even in Europe, and were revolutionary catalysts in Germany, Russia and elsewhere. Some of the Jewish intellectuals of the day were atheists- like Marx, who had no regard for the Christian religion of the nations in which they had sometimes been unwelcome. Marx had many influences that drove him toward adapting atheism, Hegelianist dialectics and Zionism into a fusion that definitely met the criterion of social philosophy. Marx formalized the first modern state theory of communist economics.
Adam Smith had published the Wealth of Nations (Capitalism) about 1775 so Marx’s Das Kapital was something of an ungrade to that economic tour de force as well as a revision. Marx’s great sociological ability was found in his analysis of the British economic and social structure of the time that described the plight and problems of the poor pushed off rural farm jobs and into cities where they were exploited and labored long hours in factories. He was correct in finding some of the downsides to capitalism that were far less than ideal from the viewpoint of workers not profiting from the system. Generally he was pretty far off at inventing a practical economic alternative to capitalism- it was early in the development of sociology and economics and Marx had to rely on his own ideas in those fields for modern and futurist synthesis and that wasn’t sufficient to create a practical theory of ideal economics for his era or any other.
Karl Marx discounted Hegel’s spiritual dialectic and transformed it entirely in to materialistic economic evolution with clash and counter-clash or thesis-antithesis (as he wrote). As an atheist metaphysics with spirit were rubbish to Karl Marx, so he killed the Hegelian spirit and like Frankenstein made a monster from the corpse that walked the Earth during the 20th century primarily.
Free enterprise is the kernel that brings life to economic progress- not top-down bureaucratic management. Corporatism can oppress free enterprise as readily as communism and other forms of totalitarianism. Writing with the Socratic irony that Kierkeguaard found to be an implicit aspect of society in that it does move along unthinking philosophically about what or why social structures are the way they are, a modern economic philosopher might have a reason to experiment with myriad political economic models packaged in a variety of ways in order to fuse progress into the current ecologically devastating state of the world economy that over-concentrates wealth, leaves a large percent of poverty at the base and does not support the maximum intellectual development of all of mankind to the real limit of their abilities.
Maybe the bottom 25% of society could have socialism and the upper 75% capitalism; with the rich obligated to provide free education through graduate school, enough money for free health care, dental and living they would be motivated to employ and promote the poor out of poverty to reduce their tax payments. Perhaps capitalism should have limited corporate size in order to promote competition and business should have tax incentives for being less entropy causing to promote ecological sustainability. There should be an infinite number of economic packages in limitless forms to model that would be improvements on the present system.