This here I think is largely the crux of our disagreement. While we see differently here, I suspect we won't truly come to an accord on this topic and may have to agree to disagree. But still, I'm willing to be proven wrong if there is enough there.
To show my thoughts here, from where I'm sitting, there is maybe one Allied Race leader who is also already largely ingratiated with their respective new faction before joining. Let's look at the list:
Highmountain Tauren: Liaison - Baine, Leader - Mayla
Nightborne: Liaison - Liadrin, Leader - Thalryssa
Mag'har: Liaison - Eitrigg, Leader - Geyarah
Void Elves: Liaison - Alleria, Leader - Umbric
Lightforged: Liaison - Turalyon, Leader - Fareeya
Dark Iron: Liaison - Moira, Leader - Moira