interesting that i've never heard of it, isn't this basically AWS Fargate? write your custom stuff in docker/kubernetes and it becomes serverless?

Do you mean that you could write a regular Flask/PHP app and it will automatically make it serverless? What about long running tasks that gets triggered by http?

To answer your question, its just a lot easier to use a serverless framework to fully utilize separate AWS services (authentication, message streaming, database) while with the solution you described would benefit from custom platform depenedent binary applications (getting ffmpeg/specialized version of PIL to work on aws lambda was a nightmare).

Hopefully somebody else can chip in here, I've never used Fargate or Cloud run but neverthless open to when i can use it.