I think people like to mention that many things aren't necessary (and I almost always see a disclaimer of, "unless medically indicated") because our birth culture says otherwise. There are many women who think certain things pertaining to pregnancy and birth are a must. They're hearing it from their OB, from their friends, from their family....people like to just offer up a different POV. Even if that OP doesn't take it into consideration, other people may. It's how we all slowly learn.
With DD I had it all done. All of it. The tests, the ultrasounds, the hospital birth, the epidural. I personally (*read* PERSONALLY) am thankful that I've read the posts that pipe in with, "well it actually *isn't* necessary unless there is a medical reason". It gave me pause and caused me to question things I never would have before and now I feel so relaxed about this pregnancy and birth because of it. No being poked by needles, no going in for tests, no going into an OB office period. This will be my first homebirth.
I think that if it doesn't apply to your case (general your) because you have a NEED for a certain test, medicine, etc. then that post doesn't apply to you (again general you) and you shouldn't get offended and feel the need to defend yourself. No one is saying you're wrong. Just that statistically speaking, baring medical issues, many things are unnecessary for a healthy pregnancy and birth and I think it's important to get that word out there.