You know, I find this a tricky one. I know and understand the guidelines but I think like everything we have to treat babies as individuals.
I agree with lulu and Mrs J that really early weaning is not a good idea. However I do think getting too hung up on some magic six months watershed is unhelpful.
I also think, and have said this on other weaning threads, that the whole allergy business has a lot more to it than weaning. My DD1 has serious multiple allergy and they were in evidence way before solids (she was breast fed).
I think that there are babies who are hungry for something else before 6 months. Seems to me that if you take your cues from your baby then you can't go wrong. I know of babies who were sitting, trying to grab food and getting very cross when denied it at 20 weeks. I also know of babies who weren't interested in food before 12 months.
We don't expect them all to walk, sit up, talk, etc at the same age. Why do we expect them all to be ready for food at the same time? Doesn't make sense.
(Yes I do understand the whole virgin/leaky gut thing. Have to having an allergic child. Repeat that IMO weaning is not major factor.)
ITA that spooning mush into a 17 week old is a ridiculous and possibly dangerous practice. But I do think that if there are people who weaned earlier than current guidelines suggest, no doubt on the advice of a HCP, than they should be allowed to have their support thread.