The problem is mainly that people think "Cool I can build everything with FaaS and it will be cheaper and scale well"

Which is wrong and can be attributed to bad serverless evangelism in the past.

Serverless is building your system with managed services and only drop-in a FaaS here and there when you need some special custom behavior.

See how far you come with AppSync, Firestore or FaunaDB. Throw in 0Auth or Cognito and then when you hit a wall, make it work with FaaS.