Claude Code has only been around for a year and change. At least for our internal tests 2 years ago Anthropic models started to at least become semi-useful but they still were not great, they struggled with structured output. Prior to that their alignment strategy made the products highly unhelpful in an API context. The past 6 months to a year is where Anthropic has really shined, they have model parity and sometimes taking the lead and more importantly their product offering on the consumer side has crushed it.
> Claude Code has only been around for a year and change.
We've been experimenting with "agent harnesses" way before that though, I'm sure the first time I tried building that sort of thing was in 2023 sometime with GPT3, and I'm like 80% confident I tried the same sort of TUI experience as CC from some random user before Claude Code even became public.