Or they have other tools that they feel are as good or better. e.g. Instruments, clang, dtrace. Valgrind is powerful, and it would be nice if it was perfectly s

Or they have other tools that they feel are as good or better. e.g. Instruments, clang, dtrace. Valgrind is powerful, and it would be nice if it was perfectly supported on OS X, but it's not the end-all-be-all of runtime analysis and profiling. And have you hit any issues with gdb that can be attributed to Apple's negligence? I think Apple's investment in clang, lldb and lld demonstrate they feel it's worth investing time and resources in having outstanding low-level development tools.