[ShellfishMeme]

Strong types aren't just a correctness guarantee, they also help to discover structure and interfaces that previously were implicit.

If a developer can jump into an unknown part of a codebase and quickly see that following a certain structure will automatically make their code work for them without needing to read all the code first and double checking if it's just a random convention versus a strict interface so they don't reinvent the wheel or build code that doesn't fit in with the existing structure, then that's worth a lot and something you cannot simply cover with tests.