The string scalarDSN data type is usefully atomic. If you need to work with the sub-parts of the underlying representation, you get to disassemble them yourself.

Seeing as you can swap in DSN for a scalar data type, what you said of scalar data types applies to DSNs as well.

By your logic, the problem isn't the compoundness of DSNs, it's the lack or perceived lack of tools to manipulate DSNs.