But some people did get drawn in by professional standards (and political content, of course), with results that were beneficial to the field.

Here is an example:

Jim Carroll and Pat Mackenzie were brought together by the icon of the British folk revival, Ewan MacColl. During the 1950s and 1960s, when American folk music and skiffle were popular in English folk clubs, MacColl led a passionate campaign in support of indigenous folk song. Jim and Pat were both listening to jazz and blues at the time but, when they heard Ewan MacColl singing industrial ballads about British working people’s lives and emotions they were completely bowled over.

http://www.folkmusic.net/htmfiles/inart558.htm

So, in so far as the collecting done by Jim and Pat made a significant contribution, "professionalism" seems to have served a useful purpose in bringing people into the field of 'folk' albeit via 'industrial ballads'.