The primary point of my comment was to remind people that most HN readers are very against cyber capabilities/surveillance/etc - so when someone calls for those agencies to do something, it is important to remember that people are against those agencies even existing, having any capabilities at all.

Now as for providing you the argument for why they should or shouldn't exist, I think it's political and I like HN's move away from political discussion so let's not have it. But I think it's not going too far to ask people to be explicit about some of the contradictions. If you look at the comment phrasing I "suggested", you'll see it's a contradiction. I don't mean to resolve that contradiction but we shouldn't ignore it - my point was to write the contradiction explicitly.

One possible way to address your question briefly would be with reference to some films and books. but we don't need to answer your question in order to acknowledge the contradiction and I wouldn't like to answer it (one way or another - why they should, why they shouldn't exist.) it's good for HN to step back from politics a bit so let's leave it at that.