Look, I'm going to be honest with you. I am a big believer in the mental side of sport, which is part of my reasoning behind supporting resting, as I believe it's beneficial for the mind as well as the body.We beat Sydney in R4 last year, 5 months (almost to the day) before we played them in the finals. After R4 this year, Sydney were still getting visits from Owen. A lot happens in 5 months.
This year we're playing them on the eve of the finals, and we have the opportunity to knock them out of top-4 considerations. Even contemplating the possibility of not doing our best to do that is insane.
There's little benefit to resting players in R22, given that there's a bye after R23.
That said, I can't see us deriving any significant psychological benefit by beating Sydney this week unless we do so by a large margin, which I think is unlikely to happen even if Walker and Sloane play. From our players perspective, doubts about whether we can do the same in finals will remain, and from the perspective of the Sydney players, they'll still have the belief that they can beat us in finals because they did as recently as last year.
I'm willing to concede there is value in keeping them out of the top four, but that has never been something I argued against.