But you will need other things... you need some kind of fronting system to tie things together, you need some sort of DB/Storage. And while you can get away with fewer admins, someone will be spending part of their time in a sysadmin role. It's more a matter of how much can get done with how many admins.
I get the point you are trying to make, but as AWS offers many services, I don't need a sysadmin for a DB (RDS, Dynamodb, ElasticSearch, S3) or for APIGateway nor for any coordination between systems (SNS, SES)
True serverless let's me offload that cost to AWS instead of having a sysadmin
Who maintains the database, schema, updates? Application deployments, testing, qa, updates? There's someone doing the job, even if it's fewer people, or someone with multiple hats.
