Anarchists don't want a fully publicly owned and planned global republic, Marxists do. Anarchists want networks of decentralized communes, Marxists do not.

The "state" for Marxists is the oppressive elements of society that make up class distinctions, such as private property rights and the current police structure, whereas for Anarchists its usually seen as a form of hierarchy entrenched with violence.

Chiefly, a decentralized network of communed does not get rid of class, but entrenches petite bourgeois class structures where each commune owns only what is within its commune, whereas Marxists want to abolish class by making all property equally owned by all in a highly developed and complex economy.

The fact that it is attributed to a very few actors and not a literal, singular actor does not negate great man theory.

The issue is that this is arbitrarily flattening of the actual material conditions. You can point out that nearly all political systems, on a long enough timeline lead to some form of collapse (Joseph Tainter is a good reference on this). But all of these things are dependent, not independent, of the systems and conditions they find themselves in. The timescales and forms can vary drastically depending on the material conditions actors find themselves in.