Types can act as good documentation and as a safeguard for stupid mistakes. But the worst bugs are due to logic mistakes, wrong assumptions or non-foreseen corner cases. Here, either types do not help, or designing the type system is so difficult it is not worth the effort, and makes many future changes more difficult.

In my previous company we used Scala (with and without Spark) for everything, and this setup pretty much allows you both extremes. There was always a middle ground to be found, where types were expressive enough that they were useful, but not too much that they came in the way.