The present reality of Lambda is quite different though. Even though the code of the function itself is more or less "business logic" (although this is a really meaningless term when we're talking about known programming languages and computers), the scaffolding around it with Terraform/CloudFormation/Serverless/etc. is substantial, riddled with quirks and is really time-consuming to figure out and update. I don't think I spend less time on this accidental complexity now when we have most of our logic in Lambda, compared to the times when we were just running Flask apps in a VM.
This is not to mention how hard one has to fight to overcome the limitations of the runtime, e.g. adding some "warmers" scripts to reduce cold-start latency (no, provisioned concurrency doesn't help and is ridiculously expensive). And then comes the bill after you accidentally created invocation loop between two functions.