Looking at The Spanish Revolution as an example to start, in Catalonia, we saw the anarchist collectivization succeed initially but then collapse due to a lack of centralized coordination. The anarchist militias refused to integrate into a unified command which lead to fatal disorganization against Franco’s army. Without a centralized state to coordinate defense, industry, and supply chains, anarchist regions were militarily and economically defeated.
More theoretically, we should all understand that Anarchism rejects all hierarchical authority, including a transitional socialist state. But in any real-world revolution, hostile capitalist states and their reactionaries and ideological proponents remain. Without a centralized state to defend borders, regulate foreign trade, and suppress counter-revolutionary sabotage, the anarchist territory would either be invaded or economically strangled. This anti-statism ultimately ends up enabling capitalist restoration rather than a growth of socialism and beyond.
Further along theoretical lines per socialist theory, after capitalist overthrow a temporary workers’ state is required to suppress bourgeoisie resistance, to coordinate large-scale industry, and then manage resource distribution. Anarchism confuses the class character of the state (bourgeois vs proletarian) with the existence of any state regardless of structure. Without a proletarian state, capital can reasserts its control through non-political means via economic coercion, private violence, market dependence, and the like. Anarchists like Bakunin rejected this thought, but Engels responded that those who ignore the necessity of a prior period of working-class political rule in favor of immediate abolition of the state will ultimately fail.
Looking to the unfortunate economic reality, modern industry (like energy grids, supply chains, rail networks) needs unified planning and dispute resolution. Without binding authority, a commune hoarding grain or refusing to send coal or other resources paralyzes other communities. Anarchism’s consensus-based systems will break down under material scarcity which will lead either to collapse or an informal hierarchy (bosses emerging without titles, not much different from capitalism today).
At the end of the day, the principles of anarchism fail historical analysis, logic (defense against capitalism without a state), traditional socialist theory in the need for proletarian state, and then material reality (large-scale coordination requires some form of authority in any interim state). If this subreddit is for discussing socialism as it is understood historically and theoretically, then anarchism should not take a visible place in this forum. This is not to say anarchist thought lacks viability as a whole, as the end goals of anarchists and communists end up the same, but anarchism ignores material conditions and reality to circumvent socialism as a means to a stateless, classless, moneyless society.