Signal has been pretty useful for the groups I learn from for my research — journalists, mostly. I spend a lot of time learning about what works and what doesn’t work for non-technical folks who are just getting started. Lately a lot of people have asked about the app, and many were surprised by some of the features beyond messaging and calls (e.g., group messaging, verification). To your main question about why I wrote this, tl;dr: Rather than revisit the same information, it saves me a lot of time to point to this link. It would have been a very different article if I wanted to shift the emphasis to the need for encryption, rather than just setting up the tools.