When I read about western intelligence agencies, one can't help but look at the last decade or so and ask, what was it they said their job was again, specifically?
[0] https://www.wiley.com/en-us/Intelligence+in+An+Insecure+Worl...
Anecdotally that claim seems untrue. Intelligence services have had a tangible effect on world history.[1][2][3]
1. https://en.wikipedia.org/wiki/Cryptanalysis_of_the_Enigma
You forgot the most important:
https://en.wikipedia.org/wiki/Battle_of_Midway
>Military historian John Keegan called it "the most stunning and decisive blow in the history of naval warfare",[9] [...] Most significantly, American cryptographers were able to determine the date and location of the planned attack, enabling the forewarned U.S. Navy to prepare its own ambush.
> Admiral Nimitz had one critical advantage: US cryptanalysts had partially broken the Japanese Navy's JN-25b code. Since early 1942, the US had been decoding messages stating that there would soon be an operation at objective "AF". It was initially not known where "AF" was, but Commander Joseph Rochefort and his team at Station HYPO were able to confirm that it was Midway: Captain Wilfred Holmes devised a ruse of telling the base at Midway (by secure undersea cable) to broadcast an uncoded radio message stating that Midway's water purification system had broken down. Within 24 hours, the code breakers picked up a Japanese message that "AF was short on water". No Japanese radio operators who intercepted the message seemed concerned that the Americans were broadcasting uncoded that a major naval installation close to the Japanese threat ring was having a water shortage, which could have tipped off Japanese intelligence officers that it was a deliberate attempt at deception.
What intrigues me is the claim "intelligence work is never useful". This is easily falsifiable with Wikipedia, which I assume even university professors deign to glance at on occasion. It's such a weird statement to make I feel like there's either more or GGP is mis-remembering something important from the book.