> That is to say, they're targeting individuals who they have no substantial reason to believe actually did anything wrong.
> That isn't true. It means it wouldn't reach probable cause.
So, investigating a crime should lead you to some evidence that you would than have a substantial reason to request a warrant to target an individual. You're letting the tail wag the dog if they can do the targeting before they know who to target. If they don't have any evidence to target a person but they suspect that person of doing something illegal then that's called a hunch. Scooby doo and his gang were great at following hunches, but that shouldn't be how the FBI operates.