"It takes a special kind of begrudgery to benefit from the work of collectors by taking and singing the songs they have passed on to us, refusing to recognise their role, then boast about it."

A long post to get to your point JC. The songs existed, it takes a special kind of conceit to believe they'd have died without the collector. Perhaps the community had no further use for them? It's a similar position to Columbus discovering America and not telling a few million natives about it first. Anon became the new authorship with the collector centre stage.
Your opening salvo was nearer the truth "They have no role in the 'folk process'...". At least it would have been if there was a folk process.