It's also easy to hire people who have AWS experience. It's getting harder and harder these days to find anyone who has actually seen the inside of a data centre.
Now more and more companies are locked in in Amazon.
Hard to find a good old Datacenter Admin.
I know perfectly well how to provision and scale a large infrastructure and can give you 99,999% availability in any application, BGP if needed.
Yet no one is interested in that. Sure I can write Ansible scripts and Terraform policies, but it's a miniscule part of my skillset and doing it on AWS is just boring compared to building the backend that powers it.