Multiple state agencies can fight over control of nodes and, if one of them somehow controls enough nodes they get such information.

If you're right that such agencies can afford to, I dunno, expend zero days to seize control of nodes, they're all going to do that. That doesn't magically create more nodes, just makes it harder to decide who (if anyone) controls them.

The most likely outcome isn't that multiple state agencies can get this done, but that none of them can despite their fervent wishes otherwise.

They don't need to control the node; good hacking and spying doesn't reveal your presence unless that is beneficial. Nothing stops multiple attackers from having access unless they want to interfere with each other.

Except, those agents didn't actually work for the Germans. Twenty Committee (because twenty = XX in Roman Numerals, a Double Cross) had identified all the German agents and offered them either indefinite imprisonment for Espionage, or service as agents feeding bogus information to their German masters (and we can infer, the third alternative was death). You can guess what most of them chose.

Twenty Committee in effect ran German Espionage in WWII. If they had destroyed all these agents the Germans would have known and perhaps, in time, the Germans would have replaced them, but instead the Germans believed they had a working on-the-ground network of agents in Britain.

The point of the story is: "Just" having accurate information when actually somebody else controls your source of intelligence isn't actually having accurate information at all, it means you're a fool. Either you have control or you do not.