While I disagree with Marx on a number of points, the quality of his general analysis is actually fairly uncontroversial, not least because it is not markedly different from the analysis of noted socialist idol *checks notes* Adam Smith in i.a. Wealth of Nations. https://twitter.com/elonmusk/status/1287824348460593154

Smith is somewhat unsystematic in his critique of rent seeking/the exploitation of labour, although it permeates both his well known Wealth of Nations as well as, more broadly, his excellent Theory of Moral Sentiment. Don't believe me? This is, verbatim, from Wealth of Nations:

"As soon as the land of any country has all become private property, the landlords, like all other men, love to reap where they never sowed, and demand a rent even for its natural produce. The wood of the forest, the grass of the field, and all the natural fruits of the earth,

which, when land was in common, cost the labourer only the trouble of gathering them, come, even to him, to have an additional price fixed upon them. He must then pay for the licence to gather them; and must give up to the landlord a portion of what his labour either collects

or produces. This portion, or, what comes to the same thing, the price of this portion, constitutes the rent of land[.]"

As for Marx, his broader point is actually, primarily, that labourers should participate more immediately and proportionally in the profit their labour generates. It is true that Marx was an avid activist and I'd also be the first to critique his general model of history,

however, there is hardly ever any informed critique of Marx, only the mewlings of dim-witted idiots who haven't read, or haven't understood, either Marx or any of the other early economists.