Does the principle of functus officio exist to allow for finality of judgments from courts which are subject to appeal?

It is clear that the principle of functus officio exists to allow finality of judgments from courts which are subject to appeal (see also Reekie v. Messervey, 1990 CanLII 158 (SCC), [1990] 1 S.C.R. 219, at pp. 222-23). This makes sense: if a court could continually hear applications to vary its decisions, it would assume the function of an appellate court and deny litigants a stable base from which to launch an appeal. ... [Emphasis added]