One of the things I think has been a failing of many Marxist-Leninist movements is the lack of long-term thinking.
People often talk about how ancoms and MLs agree on the ends but disagree on the means. However, if the long-term goal of MLs is the withering of the state, they rarely put effort into building the non-state structures that will eventually lead to that.
They should be building decentralized, democratic power. Embracing anarchists and building a culture of autonomy is how you develop a society where the state will wither. Many of the great successes of #socialism occurred when we worked together.