The key point about an answer is that it should be useful and informative, not only for the person asking the question but for anyone else interested enough to read it.
Let's take the question you link as an example. The tone of the question suggests the OP has learned some facts about black holes (I would from popular science books/TV programmes) but doesn't have any real knowledge of general relativity. My aim when answering was to answer the question, but also try and explain why we get that answer and explain some of the background. The idea is that anyone reading my answer will leave feeling wiser. Actually I'm not sure I've really achieved this since I did kind of just trot out some formulae and graph them - I really must go back to the answer and add more detail.
But to just say:
Nobody, not the best people we have, nobody, knows what goes on inside a black hole.
is massively unhelpful. It's true that we don't have a nearby black hole to do experiments on, so all our theories are just theories. However there are lots of tests of GR and it's well enough establshed that we ca feel confident about using it to make predictions (like the graphs I drew). It's also true that the region of spacetime inside the event horizon is causally disconnected from the region outside, so we'll never have experimental tests of what happens inside it. But we have coordinate systems that cross the event horizon smoothly so (apart from the wilder excesses of string theorists) there is no reason to suppose that general relativity stops working at the event horizon.
If your answer had said we don't know, but then gone on to make the points I've raised above then it would be a reasonable answer but still less informative than it could be. As it is, your answer is true but leaves the reader no better off for having read it.
There is a satisfaction in having learned and/or understood something that was new and opaque. Everyone feels this, not just us nerds, which is how the Discovery Channel makes its money. A good answer on this site should fulfill this need - hopefully more rigorously than the Discovery Channel does. Admittedly, many readers will simply take away a new "gee whizz it's like magic" fact to impress their friends with, and I have no problem with that. But maybe a few readers will have a genuine interest sparked, and even one day become physicists.