Exactly my point, but also, to add to it:

Let's say you're actually texting in a group. Even if you use perfect operational security, odds are terrible that all members of your group will perfectly uphold the same level of security every time they share their content.

One is going to slip up. He's going to get arrested. And he's going to turn the whole group in to reduce his sentence. Everyone else meanwhile has their operational security become proof of intent, proof of deliberation, proof of trying to evade authorities. They thought they were clever with the encrypted ZIP files, but the judge and jury are going to be merciless. I don't think most authorities have a problem with that.