Why?
We can't keep playing the same players all the time. We're competing in 3 competitions, one of which is the most demanding league in the world.
If Luiz picked up an injury in a game like this, people would be going nuts about why we played him when we didn't need to.
I'd much, much rather we rested players. It doesn't matter if there's one league game in the next three weeks, it is vital we win as many of them as we can, and if this helps, so be it.