From what i have read on twitter. People were purchasing max subs and using it as a substitute for API keys for their startups. Typical scrappy startup story but this has the same bursty nature as API in temrs of concurrency and parallel requests. They used the Opencode implementation. This is probably one of the triggers because it screws up everything.

Telemetry is a reason. And its also the mentioned reason. Marketing is a plausible thing and likely part of the reason too, but lock-in etc. would have meant this would have come way sooner than now. They would not even be offering an API in that case if they really want to lock people in. That is not consistent with other actions.

At the same time, the balance is delicate. if you get too many subs users and not enough API users, then suddenly the setup is not profitable anymore. Because there is less underused capacity available to direct subs users to. This probably explains a part of their stance too, and why they havent done it till now. Openai never allowed it, and now when they do, they will make more changes to the auth setup which claude did not. (This episode tells you how duct taped whole system was at ant. They used the auth key to generate a claude code token, and just used that to hit the API servers).