Why do people have so much trouble with generalities?

I’ve noticed this for a long time, but it seems to be cropping up a lot lately. Consider the statement “books are heavier than insects.” The proper way to interpret this statement is as saying something like “in general, books are heavier than insects” or “the typical book is heavier than the typical insect.” Lately, however, I’ve noticed many people (on Fluther and elsewhere) insisting that the statement should be understood as saying “the heaviest insect is lighter than the lightest book” or “the lightest book is heavier than the heaviest insect” (these being the same in their consequences). Is this just the newest fad in sophistry, or do people really not understand generalized statements anymore?

I fully expect that someone will click on the question with the intention of saying “not everyone has trouble with generalities” before realizing that the title is an example of the exact thing about which I’m asking.