This approach exploits the fact that managing permissions for humans is a very old requirement and most platforms have good support for it already. You can then issue API keys from the agent's accounts if you want to restrict permissions further.
(a notable achievement of SaaS and now AI has been to totally circumvent spending controls. You might not be able to spend $10 on a USB cable without a purchase order, but you can run up an AI bill of arbitrary size and in some places are encouraged to!)
The "it went sideways" scenario for 100k agents spawned across the world using the same bad model is completely different from humans going sideways.
What is the use of an agent with its own accounts that are separate to my accounts? What am I even getting out of it at that point?
Start with a shared credit card. Then company credit cards. Then you layer in spend controls.
Now repeat but for “agents”.
Whether this is more near term inefficiency to drive output side actual efficiency remains to be seen. But great if you’re selling tokens!