You could do that, it's true, and folks did that with node.js to shim Go before Lambda had official Go support. But being able to just create/use/share a custom

You could do that, it's true, and folks did that with node.js to shim Go before Lambda had official Go support. But being able to just create/use/share a custom runtime inside of an organization will be easier for them overtime vs. the shim method. - Chris from Serverless@AWS.