I don't, myself, recognise any defining line between the folk scene and the pop scene, or the pop scene and the blues scene, or the blues scene and the reggae scene. It's all a multi-hued picture. You can put a pin in one place and say, yep, they'd red all right, or over there, blue - but in-between there are all manner of pinks and mauves and purples. And that does for musical style, roots, methods, techniques - anything you want. The White Heather Club was Folk. The Clash were folk. The Coppers and the Kippers. Fairport. The Pogues and The Watersons. In each case different criteria, different circumstances, different objectives, different audience, different values. But all valid and good within their own terms.
All that matters is that people are not unfairly judged by inappropriate criteria. Playing trad informed music from a trad background in a pop or any other context is simply not selling out. It really isn't.