Because you don’t want to pad your bibliography and give the impression you know more about the topic than you really do. Also, the body may not match the abstract, the body may poorly substantiate its claims in the abstract, you should understand any document you’re relying on to make your point, etc.
Why is this controversial?
Edit: In fairness, some people do intend “efficient scholarship” to mean “cite any paper with an abstract that looks like it agrees with you and hope no one asks questions”, but I don’t think that’s what lukeprog means.
Always? Why?
Because you don’t want to pad your bibliography and give the impression you know more about the topic than you really do. Also, the body may not match the abstract, the body may poorly substantiate its claims in the abstract, you should understand any document you’re relying on to make your point, etc.
Why is this controversial?
Edit: In fairness, some people do intend “efficient scholarship” to mean “cite any paper with an abstract that looks like it agrees with you and hope no one asks questions”, but I don’t think that’s what lukeprog means.
I’m not sure it’s controversial, but I disagree very slightly on the margin. All your points are good. However, if
I have already read some papers from an author, and
I trust that their abstracts are honest representations of their work, and
I am not relying on their work as a basis for my own, but just pointing it out to my readers
I will cite it after just reading the abstract.