When in his retirement he tried to write about it, it was his work on traffic analysis more than his disclosing that the allies had cracked enigma that most worried the NSA who tried to stop him publishing.
Traffic analysis is in many ways more valuable than the contents of the messages.
Traffic analysis is king because who you communicate with is a low noise signal and what you communicate is usually noise.
This is well known for police work and military intelligence etc.
It’s also true for ad sales. Ad networks want the trackers on sites so they can build up a profile of you based on metadata not the content of the pages you visit themselves.
> Metadata is holographic[0] to message content
...
> [0] X is holographic to Y when the contents of X can be used to completely reconstruct Y
To say something is holographic is a claim about data, not of value. I totally buy that metadata is valuable, it could even be more valuable than the contents, but it's not a means to reproduce the message content. My ISP can tell where I bank, which is certainly valuable to observers, but it can't tell my password or the contents of my accounts, all of which I transmit. That's not a holographic reconstruction.