Earlier quoted context omitted.
They're great if you fit in with the group. If the group decides you're "different" in some way, you're going to get shunned, and shunned hard. Speaking from experience here. It works great for "normal" kids but for any kid even the slightest bit non-neurotypical, it's going to be absolute hell.
I didn't really fit into the group when I was a kid, but in hindsight I still gained a lot from them (including experience learning to better fit into groups).
Luckily for me, Girl Scouts was only somewhat bad one year. We moved, and then I hated the activities which focused around makeup and "girl stuff" instead of crafts and camping and things. My shunning was in school itself, and unfortunately the teachers didn't help at all.