It doesn't introduce any new identifiers or anything. As far as refactoring is concerned, it's just another block with nothing interesting inside it. This is sort of highlighted by the fact that we can and do plan to add syntax sugar for try!() -- if it was a language feature it wouldn't cause refactoring issues, so why is that the case here?

User defined macros (there may be some exported library macros that do this too, but try is not one of them) may define functions or implement traits or something, which might need to be modified by your refactor, which might need fiddly modification of the macro internals.

(Also, note that due to Rust's macro hygiene, all variables defined within a macro are inaccessible in the call region, unless the identifier was passed in at the call region. This helps too)