It is nothing more than a knee-jerk way to dismiss a rather easily defended position (due to the large number of closures that have been documented, ones that are more extreme or would have been considered less likely than Google Reader) by stereotyping someone's argument down to not just a "strawman" (an argument that is easily defeated), but essentially a purposely broken and laughable version of their argument so as to purposely ill-inform other people (which I feel the need to separate from a "strawman", as the goal is not to defeat the argument but to belittle the opponent). It is frankly one of the more underhanded argumentation tactics that people seem to enjoy defending here.
The reality is that Reader is a non-issue for most people here, as it isn't something you likely built your business or infrastructure around (and to the ones who ended up indirectly relying on it, that is a stretch to blame them for), but when Google randomly shuts down, cuts down, or entirely reboots APIs and services--something they have done many times, at the extremely painful end with things like Checkout and Login, but also with things such as App Engine or Charts--the fact that people seem to seriously have just forgotten how recent these things have been is distressing, and is made all the worse by people who insist on perpetuating "you are just whining about Reader" lie :/.