In Emacs you have to actively evaluate expressions (i.e., C-x C-e). This IDE apparently will evaluate highlighted expressions without interaction on the user's part. That said, you could easily write an elisp routine to do the same (evaluate region when point and mark set).
Yeah this is fairly trivial to replicate. Plus if you’re using Clojure there aren’t many side effects anyway so the effect of rolling back is largely the same.