Required? No. But if you want your views to be taken seriously then it helps to have some kind of expertise. Because you seem to be taking a very off the wall view which is at odds with reality and scientific consensus. And taking it rather confidently. In my experience the University of Lower Colon does some highly unreliable research.
First off, I answered your question directly and the first time. Continuing to harp on it is petty, especially since "bullying expertise" is not even a thing. Are you perhaps aware of Universities giving out degrees in Bully Studies?
This is not an academic duel. It's a casual discussion. My surrogate source (with postgrad degrees in psychology and education), my experience with running anti-bullying seminars with martial arts q schools, and the link thoughtfully provided by bully smartcooky

agree that a power imbalance is the classic hallmark of bullying. If you disagree, could you drop your CV and present your evidence? If not, were just two posters discussing a thread topic.
1. 'Some degree' is at least a concession on your part. But it does kind of lead to the question of why you think people who for example commit suicide over bullying do so. Couldn't they just choose not to be affected?
Suicide/depression are one thing. Bullying can surely worsen it. Kind of like HIV doesn't kill you, but opens the door wide for something much more benign to do so.
2. The difference is you have already told us that you are immune to the power of words.
That is a lie. You are lying. You are a liar.
And are defending their use as harmless. So you've given a green light to snide comments. You couldn't possibly find anything to complain about since you are immune to their effects.
That is a lie. You are lying. You are a liar.
If it's too complicated, I'll spell it out: I have not said the words of others have power over me one way or the other. For all you know, the posters here may be the most important people in my life and I hang on their every word. At no point did I say I was immune to anything. Go ahead, double check. You made that up out of whole cloth to justify your bullying behavior. You should be deeply ashamed. But bullys aren't, are they? Should you choose to respond, keep that awkward paradigm
which you have set up in mind.
You don't actually know if your words are going to upset someone else though. Other people are not necessarily like you.
True. Yet because of prior interactions/body of other posters work, I guessed 100% correctly.
3. That didn't answer the question. My question was if these words have no effect why are people using them?
You're asking me why some random other theoretically says something? I dunno. I can only answer what you asked me about my words to bully

Shalamar.
I just think that's fundamentally wrong.
Imagine a hypothetical situation where everybody who drove past or walked past you in the street hurled an abusive insult at you. That's not going to affect you? Never?
There's no 'power' there.
"Drops of water are deadly to humans. Imagine a hypothetical situation where everybody put a drop in your lungs. That's not going to affect you? Never?"