The core distinction between Marxists and many forms of Anarchists, as early as during the dispute in the First International between Bukharin and Marx, was their view not on the long term dismantling of the state - where they agreed - but the role of the state in the transition from capitalism to socialism, where the anarchists wanted the state dismantled immediately, while Marx argued the state could serve a role in a transition, itself becoming a tool to execute the changes necessary to change society.
In his works on the Paris Commune he explicitly criticised the Communards for failing to take the next step and destroy the bourgeois state. While that could certainly have been replaced with a proposed federation, a key distinction was that he celebrated the bottom up delegation of authority, which is hardly compatible with "command and control" if any part can withdraw.
As such, libertarian Marxism directly opposed to the very existence of a state became a thing, based in large part on his writings on the Paris Commune.
Well, I mean, people “forget” because equating Leninism with Marxism served the purposes of both Leninists and Western opponents of Marxism, so it became a common element of propaganda of both the USSR and other authoritarian communist regimes and the capitalist west.
Marx still believed in some sort of state-level synchronisation or command and control - otherwise he knew that you would just have lots of little communes / barracks-communists inefficiently working at cross purposes, e.g. with resource utilisation. But he never spelled out in detail how the central planning function should work - it was in effect an implementation detail. It was in this space of undefined behaviour that Lenin, Stalin and Mao created the totalitarian states that they did.
I think a lot of people forget that there was no actual collaboration between Marx and Lenin and the others. Lenin was only 13 years old when Marx died, ill and in a city on the other side of Europe.
Although there is a mass of academic detail in Marx's works, the communist manifesto itself is very thin in terms of the remedies to the problems it identifies. The 'call to action' part of the manifesto is essentially ten short bullet points, one of which is 'etc etc'.