*sigh*
The majority of the work most response officers will deal with are domestic related, especially where I am and the policies my force has regarding dealing with them. Many of them are reports similar to what the OP has described.
We deal with lots of non-crime domestics, often they are innocent enough where there's been an arguments. Many of the people I see have dysfunctional relationships, aren't particularly emotionally mature and are poor at communicating. These are often written up and filed with no further action. They often feel like a waste of my colleagues and my time. Occasionally, reports (like the OPs) are the first contact someone has where the police make an intervention to stop severe domestic abuse. Remember, DA doesn't need to be violent, there are people (vast majority are women) who live lives constantly in fear of violence but aren't actually the victim of it themselves. They may see someone else being attacked and the threats are made clear about what may happen to them if they are to "break the rules".
Take the example below:
This is a photo taken from the house of a victim of domestic abuse. They were never directly the victim of violence. Police had contact previously and the victim had strenuously denied that anything was wrong. The cards on the stairs, punctured with knives are contact cards for domestic abuse charities. The threat is clear. They had been living a life out of a horror film for years, but to outsiders, they would look exactly as the OP may have seen. Domestic abuse is far more that the stereotypical wife beater who knocks around their partner after a Stella or two. It's about power and controlling behaviour and this is often far from obvious.
Look, I get your point, the majority of couples who are seen arguing in public are not the victims or perpetrators of domestic abuse. DA does happen in all sorts of relationships, gay, hetrosexual; both men and women can be victims. Dealing with these jobs does tie up a lot of police resources.
However, fairly innocuous calls to the police have saved lives. This is not hyperbole, this is not an exaggeration, it's simply a fact. Whilst it would be great that the police only get called for the serious cases, you can't differentiate from only the behaviour you see. It often takes a lot of work to get a proper disclosure from people who are incredibly frightened and that's what the police are there to do. So in the serious cases, it is often that person who you would consider sexist and melodramatic to make the difference.