"Research shows us that an infant is not neurologically or developmentally capable of calming or soothing himself to sleep in a way that is healthy. The part of the brain that helps with self-soothing isn't well developed until the child is two and a half to three years of age. Until that time, a child depends on his parents to help him calm down and learn to regulate his intense feelings."
And yet, sleep training is not abandoning an infant. Mind your own business and stop accusing strangers who you know nothing about of abuse. You're being an a-hole.
Edit to add: attachmentparenting.org is not an objective arbiter of the research on whether or not the dogmas of attachment parenting are correct! They have a dog in this fight...
https://www.attachmentparenting.org/ensure-safe-sleep-physic...
"Research shows us that an infant is not neurologically or developmentally capable of calming or soothing himself to sleep in a way that is healthy. The part of the brain that helps with self-soothing isn't well developed until the child is two and a half to three years of age. Until that time, a child depends on his parents to help him calm down and learn to regulate his intense feelings."