Adam Smith was actually a pretty progressive guy, if a liberal. It is easy to see why people like him so much, as he fundementally believed that human empathy should be at the root of all economic transactions, and that if we operated so, the economy would naturally flourish. It is why so many libertarians hold him up as their banner, as he presents a vision of economic prosperity through freedom and fraternity. However, he also didn't ever actually visit the factories or actually talk to the workers and capitalists that he was discussing. He was a philosopher interpreting the world.

However, notice how this is quite literally the exact opposite of how Ayn Rand thinks, despite Rationalists claiming to be Adam Smith disciples.

Marx, on the other hand, has actually read Adam Smith and largely agrees with him. The question for Marx is more about why this hasn't actually happened, and what is probably nessecary to bring about a social change to make that happen. Basically, the capitalists have clearly been given an economic formula that works, why have they not actually used it as proscribed?