But it's actual lore though, another good example is Death Knights. They have three Instructors of whom teach Blood, Unholy, and Frost. It can be bland in some areas, but labeling yourself as a 'Frozen Knight' vs 'Frost Death Knight' has one difference and one title is just snowflakey. A Fire Mage vs Pyromancer.
Labeling yourself as a Havoc Demon Hunter in your TRP lets me know how your Demon Hunter fights and utilizes their abilities, though I do think using it as an IC term is a bit wonky but at the same time I don't think it's really important to worry over. It's just being direct rather than using some outlandish title. There's nothing wrong with being a Druid but calling yourself a 'Guardian of Nature' or being a Death Knight and calling yourself ' The Blood Reaper'. By all means, use exotic things such as that because calling yourself a baseline label can be bland as aforementioned but I don't think it's worth much of a debate over and I said what I said earlier to pick on him about it but in no means was it aimed to be malicious as you can see how we handled it. Also, some classes as said use those schools to differentiate even canonically.
https://wow.gamepedia.com/Destruction
https://wow.gamepedia.com/Demonology_(lore)