Before the internet, no criminals could communicate in private
Yes, before the internet, all terrorists, pædos, and other assorted bogeymen were unable to plan their dastardly deeds without being collarred by old bill.
It was impossible for said nogooders to have private conversations in their houses, in parks, in their vehicles, on the beach..
No such rascals could send coded messages via any other means, and basic one-time-pad mathematics was only invented (not simply 'discovered') when the hoodlums got broadband.
Yes, before the internet, all this was impossible, and good old plod knew everything everyone (but only if they were a baddie) knew/thought/wrote/spoke, and times were good.
We lived in a time of total Big Brother (but only for miscreants) and now that's all been ruined by the internet, encryption, and that new-fangled 'maths'