Ypyt stems from an era that somewhat compare to the old ages of MMO's.
Nowadays it's still being lived, less out of necessity but more out of entitlement.
To get mad, threaten to kick someone etc. is rather archaic/draconic in my opinion.

If there really should occur a situation, then feel free to talk about it. You might be insecure because you're new to tanking and still have to fully grasp your skillset etc.
But those tanks with a couple of dungeonclears under their belts shouldn't be so entitled.
I personally am fine if other ppl pull more stuff but that's something that happens rarely, since I usually pull everything (as long as the healer is able to keep up). All it needs for me is to collect aggro and do the same stuff, I've been doing for years ^^

Also,
my healers may pull anything they want, anytime (IF they feel like they need more action). They can count on me not to throw a tantrum but rather do what I'm in there for: Tanking.