It's a viewpoint, and there's a big chunk of truth in it, which is why it annoys people(us) a lot. I work with "world" (in the sense of non-white) musicians a lot, and am also a fanatic about the joys of English traditional music. if I am a organisng multi-cu;tural events I make sure we get the Kurdish fiddlers, the ican singers, and jigs and hornpipes as well.
    But let's be fair and listen to what the guy says. If you were organising the Fantasy World Concert featuring musicians of the last 50 years, who would you put up for the English slot? (The word "folk" is not being used, by the way, just "world"). Would it be the Stones perhaps? The Beatles? The Kinks? The Sex Pistols? Or would it be Louis Killen, the Spinners, Martin or Eliza Carthy? Now, if we are talking folk, the latter lot would be considered. But if it was just "music"., might we not take very seriously the contributions of the first four groups I mentioned?
   I can pick holes in that article, as we all can. But there's no harm in reflecting on what might just be right about it, as well.