He's not representing Argentina, he's the Pope.
It's not exactly a heresy against first world economics to say that unfettered capitalism is about as disastrous as unfettered socialism. We're extraordinarily lucky to live in the UK that has a strong sense of capitalism with a moderately robust socialist safety net. Any attempts to erode that level of social safety net while enhancing capitalism should be opposed just as much as any attempts to erode the UK's current level of capitalism while enhancing socialism. Many parts of the UK have suffered from rampant capitalism but at least the safety net has kicked in, the same rampant capitalism in the US has just resulted in tent cities, deserted towns and desperate poverty with a safety net that's seriously grudged at best.
The concern I have is that anyone who gets caught in the UK's safety net is stereotyped as a scrounger by the media and egged on by all three main parties, all chasing the elusive "focus group" approval of their policies and journalism.
You seem to be arguing that the UK has found perfection between the two extremes and policy must never deviate from this happy medium. If only life were that easy. We live in a state of constant change and what is a happy medium now may well be "wrong" in the future. Avoiding dogmatism is the thing.
Whether he represents Argentina or not, he certainly lived there for most of his life. He's just echoing the knee-jerk populist cr4p that gets people elected in South America except he didn't start bashing the US or the IMF (who of course cause all the economic problems in South America not corrupt populist politicians).
The reson why certain towns e.g. Detroit are largely abandoned is because the mayors tried to squeeze the middle class to fund all kinds of stupid vanity projects. They promptly moved and left areas of the city unpopulated. They remain so because land isn't particularly valuable or expensive in the US. It's easier to build a new Detroit in the suburbs than to rebuild the old one. Over here we have scarce land and thus it is valuable. When we have derelict land, there is a lot of commercial pressure to redevelop it. You can't rebuild Liverpool on empty land in Cheshire because there are already towns there. It's nothing to do with a social safety net.
He has no more deep insight into how to run an economy than the average pop star.