I started writing a comment on this post on why Attachment Parenting is a bad idea, and more particularly on the comments which all say It's Been Around For Thousands Of Years And It Works. The comment got a bit long so I'm going to write it here and post a link there... or something.
I've had the opportunity to observe both Western proponents of attachment parenting AND parenting in a very traditional society with a lot of co-sleeping, breastfeeding till age 2 and beyond, and carrying in slings.
The attitudes and motivations of parents are totally different. That's what makes the "babies have been brought up this way for thousands of years" argument spurious.
AP proponents discuss their practices in I have to say (as another parent) very self-righteous and self-satisfied tones. They claim loudly and proudly that their baby "won't sleep anywhere else than in our bed" while traditional society parents wouldn't crow about it - they would just quietly move a non-night-feeding baby to a sibling's bed. In most such societies there are simply not enough beds for everyone, but in some areas it has been a priority traditionally to provide everyone with a bed, and small children do get their own beds. I've only heard this reported, not seen it for myself, but those in bed-sharing areas don't regard it as child abuse by those in individual-bed areas.
Co-sleeping is safer if you don't have blankets, covers, quilts etc. And many traditional societies are in tropical areas where you don't need those things. We rejected co-sleeping on safety grounds, but have had some snooty looks from families that do co-sleep.
Likewise breastfeeding mothers in traditional societies are happy to pass their baby over to be carried by someone else when not feeding, and they carry their baby because it's practical (strollers don't work well on mud tracks, plus they cost more than a cloth carrier). AP proponents don't particularly like back carries for young babies (no eye contact), and they talk proudly of having a "velcro baby" who "won't be put down", presumably because (aged 2 or 3) they never really have.
Traditional society parents almost exclusively use back carries, even from birth, expect their child to walk when they can, and expect older siblings to take their turn at carrying a baby who can't walk (and even very small older siblings carry the ones who can't walk yet). Many of them are not shy of telling their toddlers they can't have a carry because Mama is carrying something else on her back.
And I've heard a traditional society mother happily tell her friends her talking toddler didn't really like mother's milk any more, solid food was more filling. AP parents in contrast (though breastfeeding beyond about 2 is uncommon, as commenters have said - breastfeeding till 6 is an exaggeration), are again smug and self-satisfied when their baby carries on breastfeeding and imply that when a child stops, it's because the mother wasn't committed enough.
My own parenting attitude? I'd say it was like traditional society parents: we do what's practical and what we can afford. We do use a baby carrier - the baby is just as happy in it as in a stroller, but some places have a ridiculous number of steps, and it means we can go on short hikes. We use a back carry more to save our own backs. I carry a small backpack on my own back sometimes, and the baby must then go in the stroller or on my front (he's not walking yet). We were given a front-facing stroller (sorry, no eye contact there either!), so we didn't buy one.
We've never co-slept as the medical indications for our baby were that it was less safe than for a lot of other babies. And the baby is now at the age where in a traditional society an older sibling's bed or, in fact, room would be the spot for sleeping (we don't have one of those, but the baby is in a crib in a room alone now, and seems very happy).
And breastfeeding? well, that wasn't going to happen without non-UK-approved drugs. Thankfully I haven't had anyone be so crass as to suggest to my face I should have taken these, and I've mainly listened to AP smugness over breastfeeding towards mothers who were able to breastfeed, but stopped early.
Personally, I would have loved to breastfeed for the convenience and the low cost. I hate sterilising, remembering to make up bottles of formula, taking bottles on a day out but leaving them too long so they aren't usable any more. But I'm grateful formula exists, as in former years a baby in such a situation would have been given solid food, or an odd mixture of unsterilised milk and flour. And the husband is very glad he's been able to sit and gaze at the baby adoringly while feeding, too.