That seems like an orthogonal issue to me. The assert is to ensure that the data type matches some external requirement; a quote is a structure that as 28 bytes

That seems like an orthogonal issue to me. The assert is to ensure that the data type matches some external requirement; a quote is a structure that as 28 bytes long, and if something changes to make a Quote not 28 bytes long, you'll be told. If it weren't there, the algebraic data stuff would still work fine. Edit: I say this as someone whose primary language is Haskell