i worry about it myself, too
I have no history of allergies, but DH has asthma and is triggered by dust mites and some pollens.
He loves peanuts.
I was brought up in a house with peanuts, but never really ate many myself - i probably ate a few handfuls in the pub or around christmas, but not really many at all (my dad used to eat peanuts all the time)
My DD has a peanut allergy, and rather bad eczema (officially it's acute), but she's never really had peanuts herself - I don't like peanut butter, but had a little bit when pregnant (but then I had cashew nut butter too), and she had a little bit on crackers when starting to eat solids.
I wouldn't class it as exposure, and as her eczema's so bad anyway, i couldn't tell you if she reacts to it - certainly she's not bad like your DD (i think the allergy test came back at about 50%, so the Dr said we'd bebest not to feed her peanuts deliberately, but not to worry too much about avoiding them in "may contain" foods.
She's not allergic to any other nuts, but is allergic to sesame and pollens and dust mites.
Not that keeping this stuff to a minimum has done anything to solve her eczema.
But yes, i agree, it's not necessarily a good idea to introduce something "early" just because it's advised.
I think it probably has more to do with mum's exposure to it than child's - if the mum never eats xyz, then there's no way the baby can have an immunity to it already, therefore if the baby's body goes "hang on a minute, that's a bit weird" it will build up antibodies.
But of course, i have no medical research background, so mine's only hypothesis and has absolutely no founding at all.
(more extrapolation from what research has said, really)