Medical knowledge changed in that we now know that Fathers are not the generators of life, as was the understanding until the mid-1800’s. Contraception does not necessarily kill. Sterilization and barrier methods destroy no more lives than celibacy or NFP.
Birthrates of 1.3 children per woman destroy entire cultures over time.
It was really meant as a rhetorical question. The sin is in dismembering God’s gift of sex into two separate parts of unity & procreation. I’m not any kind of a theologian; there are far better ones right here on FR (and I’m pinging one) so I understand things as analogies (the simpler the better). If someone gives you an Armani suit, you don’t say, keep the pants, I just want the jacket.
That’s why IVF is as sinful as contraception, and why I was so concerned to find a Catholic OB/GYN who would at least understand my position, even if she didn’t agree with it.