Didn’t Holdo’s plan involve modifying some spaceships so they wouldn’t be detected? Wouldn’t that involve engineers? Isn’t Rose and engineer? Why didn’t Rose know what Holdo’s plan was? Did Holdo also not tell the engineers her plan? Maybe that’s why half the ships got blown up by the First Order immediately.

That whole plotline made no sense and was completely pointless. But basically all of the plotlines were pointless in that movies.