<p>When it's not a homework-type question, a full answer is merited. People nevertheless sometimes leave hints in comments: I can't presume to speak for anyone else, but when I do that it's usually because I can't answer properly (or find a suitable duplicate) owing to lack of some combination of time, brains, &amp; interest; yet hope that the hint will help someone else to. From time-to-time it's also a factor that I feel the O.P. will find it satisfying to arrive at the answer for themself, given a nudge in the right direction (as with homework-type questions).</p>
<p>I don't know why the practice should be more prevalent on some sites than others. Perhaps on sites with higher answer rates, people assume hints are otiose—an answer's likely to come along anyway. Perhaps on some it's more the case that you know the answer or you don't, &amp; if you do it's not much trouble to write it out.</p>
