What did you think of Marx's critique of Condillac in Capital?
Are you familiar with the debates between the two school from 1894 to 1914. Notable participants were Engels publishing Volume 3, Böhm-Bawerk, and Rudolf Hilferding. This debate wasn't settled academically because the evidence was clear, but the was a world war, then the Russian revolution, and the a red scare. No one cared and the West wouldn't support this open debate because society was on the line in a very real way.
Marginalism doesn't reign supreme because it won the debate. Marginalism reigns supreme because the culture changed. Have any of the professional economist taken Marxist economics seriously?
And, since you want the leftist goals that I also want, you might want to read Bukharin's treaise on how marginalism is a theory that allows for some to have more freedoms than others.
Edit: I read the stack-exchange comment you linked to. It's one sided, reductive and dismissive. It flattens Marx to Ricardo which it clearly isn't. It doesn't engage with Marxist critiques of STV, of which there are real critiques. It conflated price with surplus value, which it has a relationship, but is not the same. Fails to understand that Marx is analyzing the role of a commodity and knows very well the role of nature in value creation. It is ignorant of 50+ years of modern empirical input-output testing on Marxist value theory. It cites a 1971 study without acknowledging work that complicates it from the 80s and 90s.
Overall, it approaches Marx not as a social theorist analyzing the systemic macro-laws of capital accumulation, but as a bad neoclassical economist trying (and failing) to build a microeconomic utility model for consumer pricing. It's a clumsy response at best.