Absolutely agreed. Even foster care itself is inherently traumatizing, no matter how good the foster parents are.
I was wrongfully taken into foster care for a couple months (due to police being called in a false accusation; the police took me without any investigation and handed me over to DFCS — my parents are actually wonderful and I couldn't have asked for a more supportive childhood), and it's positively ridiculous how severely it affected me.
My brother and my uncle both died when I was eight years old, and I was threatened, stalked, and assaulted by an obsessive ex-boyfriend in my early 20s (which ultimately led me to immigrate overseas to hide from him because nothing else worked) — and yet my brief stint in foster care was FAR more traumatic and affects me much more deeply to this day. Everything else barely rates a mention next to foster care. I don't expect I will ever again experience something as psychologically damaging.
I wasn't abused. My parents did everything right both before and after foster care, and my foster parents were fine. It was simply the forcible separation from my family at a young age that messed me up.
Of course, most kids who are taken into foster care aren't like me; they experience abuse at home and are in danger, and foster care is necessary to protect them. But how do you solve childhood trauma in these kids when saving them from abuse is, itself, a source of severe childhood trauma?