The group in this article used straight and simple PPO, so I guess GRPO isn't required. My hypothesis is that everyone was just so stunned by oai's result so m

The group in this article used straight and simple PPO, so I guess GRPO isn't required. My hypothesis is that everyone was just so stunned by oai's result so most just decided to blindly chase it and do what oai did (i.e. scaling up). And it's only after o1 people started seriously trying other ideas.