I think that is over-reaching, too.
But pragmatically, the more data they have, the more likely you are to show up as a false positive. Worst case; you handle something in a hardware store and it's later made into a bomb by a third party. You're going to need a solid alibi for that one.
Or you get placed at the scene of a protest even though you weren't present for it. Now you're on the terrorist list.
Additionally they can catch you more easily for victimless crimes, like if your fingerprints are on a bong they collect. I figure it's easy enough for them to stick you with a felony even without actively helping them get more data. So I'm trying to minimize the felonies I can be stuck with.