The primary science fiction quality of the show is that something like that could have been done as early as it was said to have been. At the time, that part of it seemed almost completely impossible. With subsequent developments, it now only seems implausible. Wild.
To me the wildest part was always that this originally aired almost 2 full years before Snowden. The premise that the government gave itself permission to read and analyze all digital traffic after 9/11 was more conspiracy than science fiction back then, but Snowden showed that basically everything the show claimed (except for the artificial superintelligence doing the analysis) was actually true. And heck, if it is not 100% true today, it probably will be very soon. I'd be very surprised if the NSA isn't tapping into the secret in-house research models at OpenAI that are still a long way from public release.