I think with physical violence, it can escalate. You punch me and "win" the fight, next time I come back with a few friends and the fight may get worse over time. And that's just assuming it's only punches. If knives or guns are involved, it can escalate really fast, and perpetuate unresolved for years, if not generations.
And I agree with you that the violence is just taking other forms. One can't punch another, so instead, we shame that person, humiliate them, embarrass them in front of their friends and loved ones. I sometimes have fear of posting on public forums, saying something that will make someone angry, and then receiving an onslaught of comments ridiculing me and beyond.
So while I think some conflict can resolve itself through merely putting on gloves and duking it out, I think more often than not conflict resolves itself much better through communicating in a nonviolent way.
I remember one message from a father to a son, for example, that said "never throw the first punch unless he is X inches taller than you". Of course, this might have been a tad to noble for the time, but still, there were norms.
On the second part, I would say that emotions are often unarticulated, which may be similar to what you're saying. For me, what I've been trying to practice is that when I start to feel angry, to say "I feel angry" instead of "what is wrong with you??" I've noticed in traffic that if someone cuts me off, I'll have a reflex to cuss out the guy or say something about him being an idiot, and then I'll pause and go, "I really just felt afraid that I would crash." I could tell story after story about how the emotion is not being clearly articulated, and that when it is, it can really realign the situation.
But, to quote James Pennebaker, author of Opening Up (a book that I read and loved) and lots of work on journaling and emotions:
"Verbally labeling an emotion is much like applying a digital technology (language) to an analog signal (emotion and the emotional experience)." --from https://c3po.media.mit.edu/wp-content/uploads/sites/45/2016/..., an article I have not yet fully read.
So, in conclusion, maybe my unarticulated is your uncontained analog signal :-D
Regarding the digital technology part, for me it's basically saying that we have this messy, organic, chemical mix of things happening within our bodies, and then we condense all of that into one word, e.g., "happy."
What fascinates me about language, and frustrates me, and does many other things to me, is the fact that when I use the word "happy" it may be describing a different internal messiness than your word "happy," and yet, the more we have in common, the more I will often assume our definitions are the same. I can't tell you how many conflicts in which I've found myself from definitions that I assumed to be shared but were in fact different, e.g., "I'm ready to leave," lol.
"Does distraction or rumination work better to diffuse anger? Catharsis theory predicts that rumination works best, but empirical evidence is lacking."
On the other hand, I've personally experienced a cathartic process that—as best as one can trace these things—brought real change, so there's no single answer about this.
If the State monopolizes violence to the point that we can’t hash things out with our fists, and there’s no room in our society to emotionally vent, then what’s left? It’s not like violence disappeared from society, it just takes different forms when suppressed.