Firstly, the distinction between "state ownership of MOP" and "worker ownership of MOP" is a false dichotomy. They are not mutually exclusive, both can be true, and if the state is a workers' state then the distinction is meaningless anyway.
Secondly, all states are "authoritarian" by definition. A state holds the monopoly on violence in its territory. Whether any form of authority and organization can be called a state is a matter of semantics. Anarchists will often acknowledge that some form of organization is needed, they are simply allergic to that authority being labeled a state.
The relevant question to ask is: what is the class character of the state in question? To fail to distinguish between a bourgeois and a proletarian state is to engage in idealism. It is an error that stems from looking only at the form of something and ignoring its actual essence or content.
All that aside, the problem remains that this issue is simply one of practicality. There is no realistic path in a world dominated by imperialism and capitalism to establish and maintain the kind of society that anarchists want without going through the socialist phase.
Until anarchists can propose a viable and practical roadmap to achieving what they say they want to achieve (without relying on magical wishful thinking like "and then everyone agrees to dissolve all authority and voluntarily work together"), it is only rational to go with the only historically proven model for building (and protecting) a society that puts people before profits, and that is the Marxist-Leninist model.
Where is the anarchist society that can resist organized imperialist aggression? Even in the most catastrophic conditions like Gaza, there is still a need for authority to organize aid, distribution of resources, defense against the genocidal occupiers. If you fail to defend your society then it is irrelevant how pure and "ideal" your socio-economic structure was.
Where is the anarchist society that can demonstrate via material results that it can outperform capitalist societies in terms of the living conditions and material abundance provided to its people? If you fail to deliver positive material conditions then people will not want to adopt or defend your system when there are alternatives they perceive as preferable.
People may be willing for a time to sacrifice their comfort for the cause if they believe in your promises, but sooner or later their revolutionary enthusiasm will be exhausted if you don't deliver something tangible.
The problems with left anarchism are much the same as the problems with right anarchism. They are both fundamentally individualist (liberal) ideologies that are built on an idealized fantasy of how they wish reality worked rather than a sober materialist analysis of how it actually works. That's why in practice both fail.