In a New York Times op-ed about government surveillance of Americans, Max Read notes how more people are now using apps like Signal to be able to communicate more securely. Then he writes,

This is more than a philosophical concern about the hypothetical violation of privacy rights; it’s a practical one....

As lawyers and civil libertarians point out, federal criminal law is so vast and complicated that it is easy to unwittingly violate it, and even innocent conversation can later be used to build a criminal case. Encrypting your communication isn’t a matter of hiding criminal activity; it’s a matter of ensuring innocuous activity can’t be deemed suspicious by a zealous prosecutor or intelligence agent. Telling a friend that a party is really going to “blow up” when you arrive is less funny when it’s being entered into evidence against you.

Then three paragraphs later, Read says this:

While the fantasy of oppressive government surveillance is appealing to the little Winston Smiths inside us — and is much more than a fantasy for many activists and journalists — practically, what most of us should fear isn’t Big Brother reading our emails, but everyone else.

So people who use apps like Signal have a very practical concern because government surveillance is sweeping up private information from Americans indiscriminately, monitoring their communications for keyphrases like "blow up", and people don't want to be mistakenly charged with a felony for an arguably poor choice of words.

But the idea that there is oppressive government surveillance is a "fantasy".