Steve already told you that refcounting isn't reached for by default, and I wanted to share an anecdote to emphasize that.

I've written a regex library, CSV parser, command line arg parser, elastic tabs and quickcheck in Rust. Behold:

    $ find ./ -type f -name '*.rs' -print0 | xargs -0 grep Rc
    $

I've definitely reached for it a few times as an escape hatch, but I've always ended up finding a cleaner approach to persist without it.

Of course, there are plenty of legitimate uses of refcounting. I just haven't hit them yet. :-)