Yes, it would be a much less dramatic headline if they'd used an ALB instead of an API Gateway, it shows the complexity of the AWS product offering though that someone picking up lambda for the first time didn't find this out.
They already have a classic ELB in place, so switching to an ALB wouldn't be a significant change in cost or capability (the ALB is often cheaper, though it's hard to tell in this case)
They already have a classic ELB in place, so switching to an ALB wouldn't be a significant change in cost or capability (the ALB is often cheaper, though it's hard to tell in this case)