He uses vim and copy paste code from web interfaces because he wants to maintain control and understanding of the code. You can find proofs of this setup on his youtube channel [https://www.youtube.com/@antirez]
Thanks. Also based on the coding rig you use models may not match the performance of what it is served via web. Or may not be as cheap. For instance the Gemini 2.5 pro 20$ account is very hard to saturate with queries.