What is the purpose of allowing a challenge after a case has been returned to the trial court following a successful appeal?

The purpose for allowing a challenge after a case has been returned to the trial court following a successful appeal was explained in Stegs [22 Cal.App.4th 115] Investments v. Superior Court (1991) 233 Cal.App.3d 572, 284 Cal.Rptr. 495: "The concern expressed by the proponents of the 1985 amendment was that a judge who had been reversed might prove to be biased against the party who successfully appealed the judge's erroneous ruling at the original trial. The amendment was 'intended to permit a party to challenge a judge who had been assigned to conduct the "new trial" of the case in which his or her decision was reversed on appeal. The term "new trial" is intended to cover situations where the case is to be retried and not merely remanded with instructions to perform some specific task' (e.g., recalculate interest)." (Id. at pp. 575-576, 284 Cal.Rptr. 495; see also People v. Gulbrandsen (1989) 209 Cal.App.3d 1547, 1562, 258 Cal.Rptr. 75.)