> I think the use case is "I haven't yet completely grokked the borrow checker and/or I don't have time to pacify it, but I would prefer not to copy potentially large data structures all over with Clone".

For basic stuff I agree, though I wouldn't use it.

> about the Rust community prescribing this as a solution to newcomers.

There's probably a sweet spot for using those constructs in not so obvious places while going through the simpler stuff in a more idiomatic way