At the risk of getting my head bitten off, I think, ghouls, that dumble was saying that forceps and ventouse isn't an evil contraption, but a life-saver in many cases - even though the use of them is horrible.
My 2pennies, confused, is that they are often used because the mother has been dosed up with painkillers/epidural and/or is stuck to a foetal heart monitor and can't move enough to labour effectively. Instrumental deliveries are much more common, for instance, with women who have epidurals, for that reason. Therefore, if it's possible for you to avoid an epidural, or pethedine, and if it's possible for you to move as your body tells you to while in labour, you are much more likely to not need instruments.
However, when needed they are horrible - but - a lifesaver certainly to the baby and sometimes to the mother, and they are an invaluable tool in modern medicine. For instance, in dumbledore's case, it's likely/possible that she would not have been able to deliver without the forceps no matter what had happened beforehand, even with a completely "natural" labour to that point.
So sometimes, you're just unlucky to need them, and lucky they're there to help. But you say that you think you maybe should not know - well knowing that an epidural is more likely to lead to instrumental delivery gives you the knowledge to make the decision not to have one, if you can cope without. And if not, well, that's fine too. Good luck, and I'm sure all will be fine :-)