I think it's simpler: imagine you're the NSA and decide to transcribe every phone call ever made to text: you'll spend gazillion in storage, connectivity and pr

I think it's simpler: imagine you're the NSA and decide to transcribe every phone call ever made to text: you'll spend gazillion in storage, connectivity and processing for the capture, and spend a gazillion squared on post-capture text analysis to find "something", like "who is communist in Atlanta", and not even be able to make it find the communists pre-emptively, before it's too late and they already donated $3 to a local chapter. There can be too much data. There are questions you cannot answer even by collecting all data, unless you have no time or food cost constraints but the value of your answer will decrease with the time distance from the moment the question was asked. In a million year you might know for sure who was communist in Atlanta during the 2000s, year by year, block by block, but you may care less by then.