Reasons for not releasing bottom-line answers to old exam questions? By bottom-line answers, I literally mean the answers on the bottom line of a solution. 

So if the question requires two pages of math with the final answer that x=5, all I'm interested in is the x=5 part. 

In other words, I just want to know whether I've got the correct numerical answer. I'm not asking for a marking rubric or 'model answer', just a verification. 


I completely appreciate the arguments against releasing worked solutions. Students can easily be robbed of learning if solutions are readily available to look at. "Oh yeah I'd have done that".
I don't think the arguments about re-using past questions quite apply here - a numerical answer isn't much help and numbers can be changed to screw people who memorise numerical answers. 


Are there any other good reasons for not releasing bottom-line answers? It just seems strange to not be able to verify your own work. 

EDIT re Dan Romik's comment: My issue here is just one of feedback. If you told me that I'd receive feedback from a lecturer or tutor (or in the real world, client or boss), I'd agree answers are moot. But the reality in university is that a lot of the learning is independent (some lecturers just say "no time" to any request), and answers are a useful feedback mechanism for students to independently spot and diagnose their own flaws.
One, it's extra work, as pointed out by @NoName.

Two, the answer may not be as helpful as you think. Just a month ago, I was grading a stats and probability exam and for one of the questions students who made two very common errors (out of 200 exams, about 40 students made those mistakes) in their work got the right answer, because the errors 'cancelled'. If bottom line answers to that exam were released for the students next year, those making those two mistakes would mistakenly think they knew the correct solution.