Marx was probably the most important intellectual of the 19th century, based on impact, but it’s generally believed he was wrong about his major predictions, and thus his theories are largely garbage. I have some sympathy for this view, but let’s look at the counter-argument.
Marx said that Communism would develop from industrial nations, with the proletariat, finally realizing they were producing all the value, taking control. What happened instead is that the two major “communist” revolutions happened in agrarian societies: Russia and China, and while China’s hard communist period (pre-Deng) advanced China significantly, they didn’t become a massive surplus society until market reform took place.
If you call a dog a duck, it’s still a dog.