And how much supplies did the CNT/FAI provide to the rest of the republic? Answer, nothing at all because they could barely handle their own disfunctional industry. The republic was not obliged to prop up their cosplaying indefinitely. Barcelona had a strong pre-war economy and should have been able to not only stand up on its own, but support other parts of the republic too.
I'm harsh on the CNT/FAI because their incompetence was a significant contributor to tens of millions of people being plunged into facsism for decades. I have possibly been too harsh on anarchists in general, mostly in my experience they are lovely people, but I don't think they're serious enough to run a revolution against militarised fascism.
I disagree with your assertion that all 3 million+ people in Catalunya suddenly fell in line with the CNT/FAI's ideology. There were possibly a few hundred thousand actual anarchists in the region, with huge numbers of people who weren't thinking about politics scared shitless of the disorganised vigilante militias going around establishing their vision of "anarchism" with zero oversight. Setting up tribunals and executing/imprisoning people with no due process. Whether they were "bottom-up" or not wasn't really relevant. It was a scary time to be in Spain and the lack of a proper system of government made things much worse for the millions of people for whom this "anarchism" stuff was weird and unknown.