Take library search tools, for example. You want to do research on hamlets; the quaint little village type of hamlet, not the brooding, more-than-likely psychotic Danish Hamlet. Aside from searching an already specialized database of relevant information or sifting through page after page of "hamlet" hits, how do you know how to evaluate your possible source materials? Abstracts, it turns out.
You see, having an abstract that tells you all of the most important information about a particular source is like suddenly being able to speed read; an abstract could theoretically allow you to be fully prepared for class discussion on a particular article without reading the actual article itself. Having an abstract is being able to tell within one page whether you should give a hoot about a piece of writing or not. It's like reading the back of the book to decide if you want to read the whole thing, only better. With abstracts the information is always accurate. Or, at least, should be, as I've discovered in today's adventure in abstraction.
No longer shall I inwardly grimace when asked to write an abstract. When you stop to think about it, writing one is the ultimate logic challenge.