Cheezy the Wiz
Socialist In A Hurry
I think that a lot of that came down to the fact that those Anarchists were in the Kropotkinite strain, and so lacked a proper understanding of class or of capitalist society, and so the ability to make any meaningful moves towards class conciousness and so an effective socialist society. (Also, that their Anarchism was often a bit half-formed, containing as much of a peasant "clubmen" mentality as a true revolutionary one.)
Oh yes, that much is certain. Of course, I would argue that nearly all anarchists lack a true sense of class consciousness.
If you look at the Anarcho-Syndicalists in Spain, who were very concious of class issues, you'll see that they cooperated more effectively with both each other and with non-Anarchist forces. Aside from anything else, they had abandoned the old Anarchist conviction that the state necessarily precedes the ruling class, moving closer to a Council Communist-style understanding of the state and ruling class as mutually re-enforcing. Indeed, in practice there is very little difference between Anarcho-Syndicalism and "Left" forms of Communism, or even some of the libertarian forms of Leninism, at least in the short term.
The Catalonian anarcho-syndicalists faced similar problems, actually. They were unable to form a unified block that could take on the Nationalists, and their relations were plagued by infighting and political intrigue.
As a side-note, the Communards also faced a very similar problem in 1871; the Versaillese were able to take on the quarters piecemeal, as the locals refused to form a united defense of the city.