And their strategy kind of worked, right? CC is the most popular agentic coding tool. Anthropic faces competition from OpenAI (potentially better model, weaker TUI tool) and from the rest (potentially worse models, weaker TUIs). So their strategy is to develop both: make their closed model and closed tool better than competition so that when people want to vibceode they will choose their ecosystem.
OpenAI Codex is a much higher quality harness than Claude Code or OpenCode, and available as open source.