Earlier quoted context omitted.
Well, in this case people should have been using Debian Testing instead of Stable. But yeah it's often that people don't understand what's Debian stable and its trade offs compared to Testing and end up unhappy with it or switching to Ubuntu (which is ~very~ similar to Debian Testing).
Unfortunately, Debian testing doesn't get security updates.
How does it works? 1. Upstream release a new version, it goes to unstable. 2. Package is tested for some days in unstable and get promoted to testing.
So telling that testing doesn't get security updates is somewhat incorrect, since you are grabing recent software. But by the other hand having too recent software also has its downside ;)