I was someone who was very anti gentle parenting and the reason is down to a single family member. When I was pregnant she had a shall we say strong willed 3 year old. One example of many is below
3 year old throw a cup of juice at mum and scream hysterically
Mum " what's wrong? What's wrong? Are you OK? " in a panicked voice
3 yo: "I wanted the blue straw"
Mum: "OK, OK, I get it for you now" - runs off and get a new drink with straw. "Are you OK to eat now?"
3 yo: instantly calms and eats his lunch.
Mum to us" he's a bit tired" 🙄
I have now had to completly distance myself as their son is a bully who targets my son so we have to avoid alot of family stuff if they are there. They have now realised that their approach is not ideal and tried to enforce boundaries but he is 9.
I avoided gentle parenting like the fucking plague. But when I looked into it a few years later I realised alot of the concepts I do naturally and its just terminology. Punishment is taboo but natural consequence is OK. In my head the "punishment " in this case would be losing any straw which is also a natural consequence.
In short gentle parenting done well works on the majority of kids. The real little shits I see in the around are actually not parented at all.