Yes, and because of the lack of record and union types in C#, it's (probably) nigh-impossible to pull off exhaustive pattern matching. However, this is still pattern matching - you can define tuple patterns which decompose the data, much like you can in F#; just with some different syntax.

I agree with you that exhaustiveness is incredibly important, and I really hope that it can be done in C# some day. However, record and union types are also a piece of this puzzle.