Thanks for going through your bins, rachel
I can't find my Bumps&Babies to see what else is said, but I agree with you - that statement on its own, while generally true, is not enough. However, we see many, many problems where the baby is not well-attached, or not as well as he could be, and where the baby is not feeding often enough. When these issues are addressed, the baby does thrive, but you are right, in some cases, it doesn't happen. Some babies need to be on or near the breast more or less all the time, which is difficult. In other cases, the baby's weight causes concern, but it could be a result of a naturally slow gaining baby. It's a complex situation, and the sentence you have quoted over-simplifies it.
'Getting more women to breastfeed' is at the very least unkind, if we leave the ones who don't manage it feeling awful. In Norway, where everyone begins breastfeeding and where only a tiny percentage switch to the bottle, women who don't breastfeed are (I am reliably informed) supported and sympathised with and it is assumed something major has occured for which the mother needs a lot of understanding. They are not told 'it doesn't matter' or 'happy mother = happy baby' or some other fatuity (when the mother plainly is not happy!).
What I mean is, it's not the drive to promote breastfeeding that is at fault per se - it's this plus maternity hospital practices that mess it up, this plus midwives and health visitors who don't know how to recognise and then fix problems, this plus ridiculous social barriers to breastfeeding, and this plus a lack of real understanding of the distress some mothers feel if breastfeeding doesn't work out.
Any reading material saying breastfeeding is 'a good thing' is a kick in the teeth for some mothers and a reminder of their grief, so yes, I agree, we should be sensitive, never glib, and think carefully about what we say, all the time.