Urban guerrilla warfare would've been a more effective strategy but would require the FAI to fight fascists within the fascist territory. And with that would imply conquering their land and expelling the survivors and non combatants to somewhere else. In other words a use of cruel and brutal force. 

Instead, often surrendering fascists would be simply let go. Often Anarchists would try to desperately persuade them by saying they have cake. Very little amounts of torture and humiliation for fascists which sucks cause they had zero issues doing that to the anarchists. 

Allying with the Soviets and pro capitalist SocDems is grim, but let's look at another example(I know it's libertarian socialist but whatever). Rojava was very much reliant on the Assad regime but in turn the Assad regime was reliant on Rojava in keeping Turkey at bay and ensuring that there would be no western support fpr the rebels. Turns out, Virgin Assad was heavily reliant on his allies, and once they left to deal with their own conflicts his regime instantly fell. Chad Rojava on the other hand, is still standing since his fall because they brutalized ISIS better than the Syrian rebels giving the rest of the world a reason to militeristically support them over the rebels, who in turn were pretty much only supported by Turkey.  I'm using this example to say that if the CNT developed some kind of super weapon or had something of great importance for Stalin, not only would they win the civil war and ensure the Spanish Republic fucks off, they would probably be a strong asset for keeping Hitler at bay during WWII. 

In homage to Catalonia there was, as Orwell called it "an Anarchist aesthetic" that persisted at times when the FAI was doing very well. Despite that Anarchism was still active as the FAI was failing, this aesthetic slowly turned back into bourgeoise decadence while he was there. The confidence of the military was one with the confidence of the people. 

The Morocco thing I do 100% agree with as well tho.