Suedonim, thanks.
Dehydration happens when - just as in this article - a baby is not feeding well, and it is not spotted. Breastfeeding counsellors see it occasionally, and the pattern is very similar to this poor mother's experience.
The right questions aren't asked, and mothers (who have not grown up seeing babies at the breast and don't really know what to look for) think just because a baby has the nipple in his mouth, he is transferring milk. This doesn't always happen, and it can become quite desperate, quite quickly.
I don't think it's especially middle class.
Babies need skin to skin contact as often and as long as possible in the early days, and a healthy, thriving baby will feed effectively from the start. If he is very sleepy, then this can interfere with the process. He needs to be producing several soft yellow poos from about day 5 and if he isn't, then this can be a danger sign. I think it is very sad that mothers are made to feel inadequate and incompetent when their babies become ill through poor feeding....it is not their fault, but the fault of a poor support system.
It is pointless, and actually quite cruel, to promote breastfeeding without the systems and training to help it succeed.