[ajmurmann]

What you say is if course true. However, with EC2 that risk is mostly limited to the code launching EC2 instances. Serverless expands that risk to your application code. There are just way more opportunities to screw up in a way that directly hits your wallet.

[rockostrich]

The same would apply to auto-scaling with EC2 instances though. If you were scaling resources based on a queue and made the mistake of adding something to the queue every time you finished something on the queue then you would start to use too many resources.

Without autoscaling, you would just have a queue that grows until the machine runs out of disk space. Either way, this was a problem with code and not event based scaling.