You seem to have missed a core point. I, as a developer, do not have the ability to make that change for whatever company I work for. Otherwise I would've canned shit like JIRA and Confluence instantly.
The 'competing' LLM providers does not matter. Companies will sign on with the big players.
The incentive is to avoid you moving to a competing LLM provider which has short and concise output.
See how a large numbers of devs switched from Claude to Gemini 2.5 because the generated code was "better".
Providing a bad service is not a competitive advantage.