It is a thing; unfortunately it's not officially supported but I also find it crazy that so many developers are fine doing dev directly on "the cloud", as if that's a reasonable use of their time.
Lack of understanding, I think every new dev to serverless will have this stage of frustration, then eventually will find a way to do better with creative ideas, I myself never run lambda in the cloud I write a UT for my handler and assume I know the input and the expected output, I mock everything except step functions I use the official jar from AWS.
https://github.com/lambci/docker-lambda
https://github.com/localstack/localstack