I tried to play devil's advocate and say -- if we can imagine creative bad things, there is a chance that sooner or later someone else will imagine them, too; but if we think about the idea first, we can find a defense. Something like inoculation.

But the problem is: we are usually not thinking about the defense, only posting bad ideas. And even if we would post a hint at solution, if a few years later someone takes the idea seriously, people will probably already forget that the solution was posted here. Also, using the same argument, if we can find a quick solution now, most likely other people will be able to find it later if it will be necessary. Yet another problem is that attack is usually more simple than defense, so contributing equally to both sides creates a negative outcome.