usability testing – Being told to moderate other designer’s tests

I want to ask if this is common practice or even a good practice.

On my ux team, we are being told that no one will moderate usability tests for their own projects. We will do all the work and prep for the tests such as figuring out tasks and writing the script but another designer from the team who has no knowledge or involvement on the project will conduct and moderate the tests.

Does this make sense? Their justification is that this will remove bias and stop the moderator from doing things like hinting to users to click that button or things like that. Which I find ridiculous that a moderator would not know to ask leading questions. I think it’s a waste of time to have to learn someone else’s project just to do moderating and never to be involved in that project again. Some people on the team and upper management believe having someone who doesn’t know the project doing the moderating is best practice because this is what they learned from a ux boot camp course.

My team wants proof that other ux teams do not work this way or UXers believe otherwise.

How does your team work? What do you think about this?