You’ll see anarchists praising Rosa Luxemburg, who if they had actually read her writings – they would see that she was very clearly one of the “authoritarian” socialists that they rail against so much.
You see them praise the Black Panthers, who were supported financially by the DPRK and aligned themselves with the Juche ideology of Kim Il Sung.
They even praise Thomas Sankara, who purged anarchists and arrested syndicalists.
If these people had succeeded, i have no doubt in my mind that anarchists would call them “tankies,” they would call their experiments “capitalism with a red flag.” And I also have no doubt in my mind that if the October Revolution, Chinese Revolution had been crushed, they would hail Lenin and Mao as proletarian heroes.
It is easy to support failed attempts because then they can imagine that this time those folks would have done things “perfectly” or in other words, the way the person imagining it would have done things. Without any of the messy details of having to work in the real world with real conditions.