A red herring is a bait planted specifically to derail a conversation.
I will make an example to demonstrate this in a setting which is less loaded.
Beware that all analogies are flawed in essence, so a direct transfer to our conversation will be difficult, especially since I am trying to be blatant. But since I want to answer your question of where the red herring lies I feel like that is the easiest way:
A (raising an issue): This hole in the wall sucks, I can't stand it. At least if we were in a tent we could sew it shut.
B (planter of herrings): So you'd rather live in a tent than in a house? Don't you know that tents are generally worse than houses?
C (the innocent bystander lead astray): I also much prefer houses. You hear so many bad things about them, but in the end nothing is better. No caves, no huts, and certainly no tents. I'd pick a house any day of the week.
Did you notice that we are no longer talking about the hole in the wall?
The hole could be required for mold-prevention, it could just be an oversight that is actually fixable, it might be a trade-off. But since we are no longer talking about the hole we will never know.
> ... but ”With a dictator you have full responsibility concentrated in a single person” is simply not true. Dictorships are master minds of shifting blame.
This is you talking about the hole in the wall. I am also not convinced by the original argument, but I do believe that there is some substance to be explored.
> ... I’m obviously biased as a European but I’d pick the eu any day.
This is you falling for the red herring. We don't know if the original poster lives in the EU. We don't know if they prefer it to a dictatorship, but it also does not matter.
The original qualms are that there is seemingly no single point you can go to to stop the endeavor once and for all, which in this context is encryption backdoors within the EU.
We could be talking about how the same mechanics that make this so frustrating are useful elsewhere; find out or explain why the things are the way they are. We could be uncovering a valid flaw in the system just waiting to be fixed; conclude that things don't have to be this way.
Instead, we ask ourselves if we like living in the EU better than in other places.
We've lost the plot, so to speak: There is no more insight to be had.
This is what makes a red herring so obnoxious to deal with.
It is an easy trap to lay if you don't want to think about something or hinder someone, but takes so much effort to recover from.
In the tent-example it is easy to see that we completely derailed and stopped talking about what matters. Unfortunately, reality is much more subtle and not everyone has the same goals in mind. At least on HN I'd like to try and keep discovery in focus and once we reach the stage where it's only about opinions there is nothing more to discover.