Why isn't sinking pass used in default pipeline?

Hi all,
I recently found out that LLVM has a sinking pass (Transforms/Scalar/Sink.cpp). Does anybody why it’s not used in the default opt pipeline? I see it supports sinking a value down to its users even if they are in different blocks, which InstCombine for example (which implements sinking too) is unable to do. Are there any known issues with the pass?