AFAIK it's already considered a best practice to set up separate accounts for development and production (https://blog.codeship.com/separate-aws-production-and-develo...). Having a hard cap on an account dedicated to development would help a lot IMO.

Assuming your revenue and your AWS bill are strongly correlated, I agree. However, when a free service or a bug can increase costs by orders of magnitude without a corresponding increase in revenue your choices are to eat it (not sustainable, for most of us), throttle, or stop. Throttling is hard, so stopping is often the best choice.