A priori it seems like a good guess. In any academic discipline, at the thesis level and above, originality is necessary for your work to be perceived as having any value, But most complicated questions with one true answer have a thousand false answers. Once people have beaten you to the true answer, it's going to be easier to be original if you go for one of the false ones, so long as you're in a discipline where verifying truth or falsehood is harder than obscuring it.
I suspect a good bellwether for identifying such disciplines is the way they treat repetition of existing truths. A lemma in a math paper might be "obvious", a paper with too many obvious lemmas might be "too verbose", but there's never any suggestion that the lemmas are "trite" or that the reviewers would prefer to read their converses instead.
This thread has produced some interesting commentary around whether philosophers actually want to answer their own questions, or whether they enjoy sounding profound by debating big questions but don't want to lose that opportunity for profundity by finding single correct answers to them.
I don't quite disagree with the latter theory: the main reason I quit academic philosophy was exasperation that people were still debating questions where the right answer seemed obvious to me (like theism vs. atheism, or whether there was a universally compelling morality/aesthetics of pure reason), and worry that my philosophical career would involve continuing to debate these issues ad nauseum rather than helping to solve them and move on to the next problem.
But when I explained this to a particularly sarcastic friend, he summarized it as "So you think philosophy is useless because not everyone agrees with you?"
The problem isn't that philosophers never come up with solutions. The problem is that they come up with too many different solutions.
Science has solved many scientific problems, and anyone wondering what the solution is can look it up in a book or on Wikipedia. Philosophers have also solved many philosophical problems, but it is full of so many distractions and false solutions that anyone wondering which proposed solution is correct will have to become nearly as good a philosopher as the person who solved it in the first place. It's much easier for science to settle its disputes via experiment than for philosophy to settle its disputes via debate.
I am wary of criticizing the discipline of philosophy simply on the grounds that not everyone in it agrees with me. But I also don't want to let it off and say it's okay that they've managed to go so long without coming to any answers, when it seems to me that settling at least some of the easier problems is not that difficult.
How do we tell the difference between a discipline that doesn't really seek answers and a discipline which honestly seeks answers but just can't agree within itself? And how can philosophy do something about its level of internal disagreement without having to apply the "kick out everyone who disagrees with Less Wrong" solution?