CC-immune mobs still give you windows, depending on the mob. For example, if a mob starts to cast and you make distance during the cast time, etc., there are definitely options that are going to be there beyond just “Have pet taunt”.
Kiting to get stacks off is part of the Necrotic design, so if that’s the bugbear a person has, yes it won’t go away. There is going to a significant feel difference if you can more reliably do it and go right back into tanking mode. There are going to be more situations now where one person on their own can facilitate an effective drop, which in itself will in theory also make “suboptimal” groups more effective.