Common, yes, although extremely common, that depends on the codebase and its goal. But they are not the default, and that what makes them system languages.
Not really, because they are not Automated Reference Counting, rather manual with explicit clone operations, in some scenarios.
Also contrary to systems where reference counting is part of the type system, and not library types, they aren't able to optimize counts away.
When this happens is as side effect of the compiler optimizing away inlined code, but not by pairing inc() with dec() operations that never leave scope.
