What you're saying isn't necessarily mutually exclusive to what gp said.

GPT-2 was the most impressive leap in terms of whatever LLMs pass off as cognitive abilities, but GPT 3.5 to 4 was actually the point at which it became a useful tool (I'm assuming to programmers in particular).

GPT-2: Really convincing stochastic parrot

GPT-4: Can one-shot ffmpeg commands

Sure, but the GP said "the most major leap", and I disagree that that was 3.5 to 4.