Thinking like this both baffles me, but also makes me happy because there will always be a need for people like me, infra. AWS is not a magical tool that will replace your infra team, it is a magical tool that will allow your infra team to do more. I am the infra team of my startup and I estimate that only 50% of my time is doing infra work. The rest is supporting my peers, work in frameworky stuff, solve dev efficiency issues bla bla.

Lets say that you operate in an AWS-less environment, with everything bare metal, in a datacenter. Your GOOD infra team has to do the following:

Hardware:

- make sure there is a channel to get new hardware, both for capacity increase and spares. What are you going to do? Buy 1 server and 2 spares? If one of the servers has an issue, isn't it quite likely that the other servers, from the same batch, to have the same issue? Is this affecting you, or not? Where do you store the spares? In a warehouse somewhere, making it harder to deploy? In the rack with the one in use, wasting rackspace/switch space? Are you going to rely on the datacenter to provide you with the hardware? What if you are one of their smaller customers and your requests get pushed back because some larger customer requests get higher priority?

- make sure there is a way to deploy said hardware. You don't want to not be able to deploy a new server because there is no space in the rack, or no space in the switch. Where are your spares? In a warehouse miles away from the datacenter? Do you have access to said warehouse at midnight, on Thanksgiving? Oh shit, someone lost the key to your rack! Oh noes, we don't have any spare network cable/connectors/screws...

Software:

- did you patch your servers? did you patch your switches?

- new server, we need to install the os. And a base set of software, including the agent we use to remote manage the server.

- oh, we also need to run and maintain the management infra, say the control plane for k8.

- oh, we want some read replicas for this db, not only we need the hardware to run the replicas on (and see above for what that means), now you need to add a bunch of monitoring and have plans in place to handle things like: replicas lagging, network links between master and replicas being full, failover for the above, master crapping out yada yada.

I bet there are many other aspects I'm missing.

Choices:

Your GOOD infra team will have to decide things like: how many spares do we need, is the capacity we have atm enough for the launch of our next world-changing feature that half the internet wants to use? Are we lucky enough to survive a few months without spares or should we get estra capacity in another datacenter? Do we want to have replicas on the west coast or is the latency acceptable?

These are the main areas of what an infra team is supposed to do: Hardware, Software and Choices. AWS (and most other cloud providers) is making the first 2 points non issues. For the last area you can do 2 things: get an infra team (could be a full fledged team, could be 1 person, you could do it) and teoretically you will get choices tailored to what your business needs OR let AWS do it for you. *AWS might make these choices based on a metric you disagree with and this is the main reason people complain*.