You can patent a technology and not put every single parameter and process optimization and detail of supporting systems into the patent. Semi fabrication is pretty much the most complex manufacturing process that humans do anywhere.
It's like building a nuclear bomb. Any high school physics nerd knows perfectly well how it works, but the US performed over a thousand nuclear tests for a reason. The fine tuning is important.
And those bombs were pathetically weak compared to modern weapons... chip fabs don't just have to turn out one wafer per year, they have to be profitable.
I find that extremely hard to believe. If you invent a novel type of bicycle gear mechanism, German patent law requires you to write a tutorial on the most cost effective way you found to machine each part, the particular grade of steel you found to be the best trade-off between price and performance to maximize profit, and your process for assembling it in the factory broken down into the step performed at each worker's station? Do they make you submit your CNC programs directly to the patent office for publication? This is all potentially extremely valuable IP that's not going to be found in the patent filings.
What do they mean by an "effort that pilfered as much as $8.75 billion in patented American technology"?