Yep, that's pretty much a lambda. But then you need to sandbox the execution because really it can do anything, which adds overhead at scale.

And is it really that much better? I think not.

If you want to do anything nontrivial, yes, probably. This hacked-together YAML syntax seems very irritating to write more complex programs in. And it probably needs sandboxing of its own to some extent, as it looks like it can do infinite loops.