Sizes are different. Before “AI” went mainstream, those in machine learning were very excited about word2vec and reinforcement learning for example. And it was known that there will be improvement with larger size neural networks but I’m not sure if anyone knew for certain how well chatgpt would have worked. Given the costs of training and inference for LLMs, I doubt you can see nerds doing it. Also, previously you didn’t have big tech firms. Not the current behemoths anyway.