It's not about what you personally find abhorrent, though. If you don't like the idea of a late term abortion, you don't have to have one.
It's also about teenage girls with unreliable periods finding out they are pregnant at 20 weeks and not being able to arrange an abortion in time.
It's about a woman who has become homeless who feels she cannot adequately care for her existing children while carrying on with her pregnancy.
It's about a woman who has fled an abusive relationship and is just starting to get her life back together and has found out she is 23 weeks pregnant. She had the implant. She doesn't get periods.
I don't say "as early as possible, as late as necessary" because I think having a late term abortion for shits and giggles is fine. I say it because I think the alternative is worse, and why does the woman who presents at 23+5 not deserve the same options as the woman who presents at 10 weeks or 16 weeks?
It's a very small proportion of women who have abortions at 20+ weeks (I think about 1.4%) but it has remained steady, while the number of 14-20 week abortions has fallen. This suggests there are reasons around this we haven't or can't address.
And I will dispute that carry a child to term in itself is not harmful. A teenager may be bullied at school for giving her baby up. An older woman may not be able to find a job if she is visibly pregnant. A woman who gives her child up may be ostracized by her relatives or harassed by her partner's family. I think it's easier to keep an abortion a secret in the second trimester, because people won't usually be sure. With adoption, there is no hiding it.
And you are bringing an unwanted child into this world. Adoption, in and of itself, is harmful to children as well- it shouldn't be presented as the easy option for everyone.