> it's boring for everyone involved
Speak for yourself: I get upvotes every time (up to 22).
> You don't have to stamp 'incorrect' on every comment you think is wrong
New people often make the same mistake about privacy and I choose to correct them, because I think it's very important. It never was about "keeping the discussion going" for me. Quite the opposite, actually.
It's mostly a classical "nothing to hide argument" (https://en.wikipedia.org/wiki/Nothing_to_hide_argument), which is unbelievably popular, sadly. There are hundreds of threads trying to explain it to someone every month, with all the same arguments, reworded. My posts stop this repeated discussions, because nobody found a counterpoint (yet?). From this reasoning, I believe it's worth to copy-paste instead of ignoring (and letting the discussion go the same way again), or linking (and loosing the attention of most observers who, quite reasonably, don't want to click a lot).