Good points JP.
But this brings up another failure of our system is this: even when law enforcement and other authorities have been informed about potentially dangerous individuals, they often do nothing. Sadly the case of Nikolas Cruz gives ample proof of that
I have to say I am sorry to see the demonization of the FBI on this. Obviously they dropped the ball, and there needs to be an investigation, but I think some in the right have jumped on this because of the current political climate. Somehow the bureau is being portrayed as a left wing organization, which is ludicrous if you know anyone who actually works there, they tend to be quite conservative, like most law enforcement organizations everywhere.
The bureau gets hundreds of thousands of tips every year. With limited resources, they do a very good job of prioritizing and acting on the most urgent. Obviously there are going to be cases where they would have acted differently, had they known, Hindsight is 20\20 vision, as they say. If it's a case of ineptitude, let the chips fall where they may, but I personally know a few people in the bureau, they are all hard-working, patriotic and dedicated to fighting crime as best they can, nobody would knowingly ignore an obvious threat.
Like almost all governmental organizations, it's not as dynamic and quick to change as it could be and that needs to be fixed. It is very case oriented, attempts to be more intelligence driven (i.e. anticipating issues rather than reacting to them) do not go far enough, the culture is too entreched. I'd like to see this issue drive that, but I don't see that happening, instead of looks like they will probably replace the current director, which will do nothing but demoralize those who work there.