Many data engineering problems are impeded by strong typing, particularly type transduction applications (translating between a database type system and a transport such as Avro, for example). While in many cases that is somebody else's problem -- it is solved in a library -- when it isn't the strengths and facility of a dynamic language can save you considerable code complexity and maintenance. Type control is often…
From the readme they describe it as "robust" and having a high level of type safety, so I'm guessing they're just leaning towards the "learn about bugs up before they hit production" end of the spectrum than you.
Then again I don't do any of this data engineering stuff so maybe it doesn't matter too much if it doesn't work reliably?