Rhubarb and others: of course mothers need to know that bf is not without problems, and where to go if they do have problems, and to have confidence in the fact that problems can be adequately resolved.
But I don't think any pregnant mother needs an A-Z 'shopping list' of possible problems all the way from abscess to (um.....) zore nipples :) taking in thrush, mastitis and everything else...any more than anyone needs to know about all the different illnesses babies and toddlers might succumb to.
Sore nipples are indeed one of the most common issues, and while it's not true that 'if you are sore the baby can't be latched on right', I wish I had a quid for every mother I have seen who's been told the baby is on fine, and he just isn't. Even if he looks ok, then something is going on in his mouth that makes it not ok. It's then up to the supporter to help the mother amend the position, and this is a skill that gets better with practice.
Could be tongue tie, for instance, causing the prob.
Bleeding or cracked nipples are caused because the skin is broken/grazed. This has to be because the nipple is being compressed instead of being down the throat (apart from maybe excema or other dermy probs).
Generalised tenderness can indeed be the body getting used to the new sensation, but very often, amendment of the position by a skilled person helps a lot with that.
BTW, Rhubarb, there are very few situations where the baby would really be better off having formula than breastmilk. Poor diet, (some) medication, alcohol.....absolutely not reasons to ff.
Some heavy-duty anti-psychotic meds, chemo and other treatment for cancer, are a different kettle of fish.