> Maybe it was a user error
Yes, there are a zillion ways to wrap a long piece of cloth (people have been doing this for at least thousands of years), and there must surely be one of them that works for any body shape. The wrap takes a bit of practice and is definitely slightly slower to put on/off than some of the carriers though (maybe an extra 1 minute).
The baby bjorn I adjusted once and it was good for months. It had clips to make it easy to take the baby in and out and for quick release when going through things like airport security.
My only complaint was that it was hard to do the clip in the back because I think it is designed for women who have a lot of experience clipping things behind their backs.