That's hardly a debunking of the thesis that violence has decreased. It cites no data, but simply declares in vague terms that some parts of the world are still

That's hardly a debunking of the thesis that violence has decreased. It cites no data, but simply declares in vague terms that some parts of the world are still violent and the sum of those parts is non-negligible, which is completely unrelated to the claim that violence has decreased. The notion that fifty years ago "even starter jobs offered comfortable salaries" will come as a shock to people who lived then, barely getting by on piecework or similar marginal occupations. There were certainly classes of jobs where entry-level positions paid "comfortable salaries" but those jobs weren't much use to you if you were non-white, female, gay, or even from the wrong nominally-white ethnic group. Things aren't as good as they could be, but they are still a lot better than they were by many, many measures. They are worse by a few measures, and we should be concerned about that, but in general the trend is in the right direction.